你要知道的NSURLSession都在這里
轉(zhuǎn)載請注明出處 http://www.reibang.com/p/167e7e2cbc9e
本系列文章主要講解iOS中網(wǎng)絡(luò)請求類NSURLSession的使用方法進(jìn)行詳解虎锚，同時(shí)也會以此為擴(kuò)展谤职，講解SDWebImage中圖片下載功能的源碼分析吮成，講解AFNetworking相關(guān)源碼分析。本系列文章主要分為以下幾篇進(jìn)行講解偿枕，讀者可按需查閱徙硅。
- iOS網(wǎng)絡(luò)——NSURLSession詳解及SDWebImage源碼解析
- iOS網(wǎng)絡(luò)——SDWebImage SDImageDownloader源碼解析
- iOS網(wǎng)絡(luò)——AFNetworking AFURLSessionManager源碼解析
- iOS網(wǎng)絡(luò)——AFNetworking AFHttpSessionManager源碼解析
AFNetworking AFURLSessionManager源碼解析
前面幾篇文章講解了NSURLSession的基礎(chǔ)使用方法以及SDWebImage在下載圖片時(shí)是如何使用NSURLSession，來完成下載任務(wù)的唉俗，本篇文章將閱讀AFNetworking是如何封裝NSURLSession來提供便捷的網(wǎng)絡(luò)請求功能。
AFNetworking的使用方法就不贅述了配椭，我們經(jīng)常使用AFHttpSessionManager來發(fā)起一個(gè)GET或是POST請求虫溜，該類是繼承自AFURLSessionManager并在其上進(jìn)行了一個(gè)封裝，提供了更加便捷的接口來發(fā)起網(wǎng)絡(luò)請求股缸，所以本篇將詳細(xì)講解AFURLSessionManager是如何封裝NSURLSession的衡楞，建議讀者對照源碼閱讀。
首先看一下頭文件的聲明:
//AFURLSessionManager類實(shí)現(xiàn)了NSURLSession相關(guān)的眾多協(xié)議敦姻，用于幫助我們進(jìn)行數(shù)據(jù)的處理
@interface AFURLSessionManager : NSObject <NSURLSessionDelegate, NSURLSessionTaskDelegate, NSURLSessionDataDelegate, NSURLSessionDownloadDelegate, NSSecureCoding, NSCopying>
//豬腳瘾境，NSURLSession 作為一個(gè)實(shí)例變量，AFN發(fā)起的網(wǎng)絡(luò)請求都是通過該session創(chuàng)建的task實(shí)現(xiàn)的
@property (readonly, nonatomic, strong) NSURLSession *session;
//NSURLSession delegate方法執(zhí)行隊(duì)列
@property (readonly, nonatomic, strong) NSOperationQueue *operationQueue;
//響應(yīng)序列化镰惦，不是本系列文章的關(guān)注點(diǎn)寄雀，有興趣的讀者可以自行閱讀源碼
@property (nonatomic, strong) id <AFURLResponseSerialization> responseSerializer;
///-------------------------------
/// @name Managing Security Policy
///-------------------------------
//安全策略，用于https等需要驗(yàn)證的地方
@property (nonatomic, strong) AFSecurityPolicy *securityPolicy;
#if !TARGET_OS_WATCH
///--------------------------------------
/// @name Monitoring Network Reachability
///--------------------------------------
//監(jiān)測網(wǎng)絡(luò)連通性陨献，使用AFNetworkReachabilityManager盒犹，讀者可自行閱讀相關(guān)源碼
@property (readwrite, nonatomic, strong) AFNetworkReachabilityManager *reachabilityManager;
#endif
///----------------------------
/// @name Getting Session Tasks
///----------------------------
//前面那個(gè)session管理的data upload download task的集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionTask *> *tasks;
//前面那個(gè)session管理的data task的集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDataTask *> *dataTasks;
//前面那個(gè)session管理的upload task的集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionUploadTask *> *uploadTasks;
//前面那個(gè)session管理的download task的集合
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDownloadTask *> *downloadTasks;
///-------------------------------
/// @name Managing Callback Queues
///-------------------------------
//完成網(wǎng)絡(luò)請求后執(zhí)行回調(diào)塊的隊(duì)列，如果為nil則使用主隊(duì)列
@property (nonatomic, strong, nullable) dispatch_queue_t completionQueue;
//完成網(wǎng)絡(luò)請求后回調(diào)塊的
@property (nonatomic, strong, nullable) dispatch_group_t completionGroup;
///---------------------------------
/// @name Working Around System Bugs
///---------------------------------
//background類型的session是否嘗試重新創(chuàng)建上傳任務(wù)
@property (nonatomic, assign) BOOL attemptsToRecreateUploadTasksForBackgroundSessions;
///---------------------
/// @name Initialization
///---------------------
//初始化函數(shù)眨业，根據(jù)指定NSURLSessionConfiguration創(chuàng)建session
- (instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER;
//設(shè)置session無效急膀，cancelPendingTasks標(biāo)識是否取消session中正在執(zhí)行的任務(wù)
//內(nèi)部還是調(diào)用NSURLSession的invalidate方法
- (void)invalidateSessionCancelingTasks:(BOOL)cancelPendingTasks;
///-------------------------
/// @name Running Data Tasks
///-------------------------
//根據(jù)指定的request等信息創(chuàng)建一個(gè)NSURLSessionDataTask任務(wù)
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler DEPRECATED_ATTRIBUTE;
//根據(jù)指定的request等參數(shù)創(chuàng)建一個(gè)NSURLSessionDataTask任務(wù)
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
uploadProgress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
downloadProgress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
///---------------------------
/// @name Running Upload Tasks
///---------------------------
//根據(jù)指定request fileURL等參數(shù)構(gòu)造一個(gè)NSURLSessionUploadTask任務(wù)
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
fromFile:(NSURL *)fileURL
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
//根據(jù)指定request和data等參數(shù)構(gòu)造一個(gè)上傳任務(wù)
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
fromData:(nullable NSData *)bodyData
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
//根據(jù)指定的request構(gòu)造一個(gè)上傳任務(wù)
- (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request
progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;
///-----------------------------
/// @name Running Download Tasks
///-----------------------------
//構(gòu)造下載任務(wù)
- (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request
progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
destination:(nullable NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(nullable void (^)(NSURLResponse *response, NSURL * _Nullable filePath, NSError * _Nullable error))completionHandler;
//構(gòu)造下載任務(wù)
- (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData
progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
destination:(nullable NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(nullable void (^)(NSURLResponse *response, NSURL * _Nullable filePath, NSError * _Nullable error))completionHandler;
///---------------------------------
/// @name Getting Progress for Tasks
///---------------------------------
//根據(jù)NSURLSessionTask獲取對應(yīng)的任務(wù)完成進(jìn)度NSProgress
- (nullable NSProgress *)uploadProgressForTask:(NSURLSessionTask *)task;
//根據(jù)NSURLSessionTask獲取對應(yīng)下載任務(wù)的進(jìn)度NSProgress
- (nullable NSProgress *)downloadProgressForTask:(NSURLSessionTask *)task;
///-----------------------------------------
/// @name Setting Session Delegate Callbacks
///-----------------------------------------
//設(shè)置session無效時(shí)執(zhí)行的回調(diào)塊
- (void)setSessionDidBecomeInvalidBlock:(nullable void (^)(NSURLSession *session, NSError *error))block;
//設(shè)置session收到challenge時(shí)執(zhí)行的回調(diào)塊
- (void)setSessionDidReceiveAuthenticationChallengeBlock:(nullable NSURLSessionAuthChallengeDisposition (^)(NSURLSession *session, NSURLAuthenticationChallenge *challenge, NSURLCredential * _Nullable __autoreleasing * _Nullable credential))block;
///--------------------------------------
/// @name Setting Task Delegate Callbacks
///--------------------------------------
//設(shè)置session需要新的流時(shí)執(zhí)行的回調(diào)塊
- (void)setTaskNeedNewBodyStreamBlock:(nullable NSInputStream * (^)(NSURLSession *session, NSURLSessionTask *task))block;
//設(shè)置session的任務(wù)需要執(zhí)行重定向時(shí)執(zhí)行的回調(diào)塊
- (void)setTaskWillPerformHTTPRedirectionBlock:(nullable NSURLRequest * _Nullable (^)(NSURLSession *session, NSURLSessionTask *task, NSURLResponse *response, NSURLRequest *request))block;
//又是代理方法執(zhí)行時(shí)需要執(zhí)行的回調(diào)塊
- (void)setTaskDidReceiveAuthenticationChallengeBlock:(nullable NSURLSessionAuthChallengeDisposition (^)(NSURLSession *session, NSURLSessionTask *task, NSURLAuthenticationChallenge *challenge, NSURLCredential * _Nullable __autoreleasing * _Nullable credential))block;
//同上
- (void)setTaskDidSendBodyDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend))block;
//同上
- (void)setTaskDidCompleteBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, NSError * _Nullable error))block;
///-------------------------------------------
/// @name Setting Data Task Delegate Callbacks
///-------------------------------------------
/**
Sets a block to be executed when a data task has received a response, as handled by the `NSURLSessionDataDelegate` method `URLSession:dataTask:didReceiveResponse:completionHandler:`.
@param block A block object to be executed when a data task has received a response. The block returns the disposition of the session response, and takes three arguments: the session, the data task, and the received response.
*/
- (void)setDataTaskDidReceiveResponseBlock:(nullable NSURLSessionResponseDisposition (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLResponse *response))block;
//同上
- (void)setDataTaskDidBecomeDownloadTaskBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLSessionDownloadTask *downloadTask))block;
//同上
- (void)setDataTaskDidReceiveDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSData *data))block;
//同上
- (void)setDataTaskWillCacheResponseBlock:(nullable NSCachedURLResponse * (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSCachedURLResponse *proposedResponse))block;
//同上
- (void)setDidFinishEventsForBackgroundURLSessionBlock:(nullable void (^)(NSURLSession *session))block;
///-----------------------------------------------
/// @name Setting Download Task Delegate Callbacks
///-----------------------------------------------
//同上
- (void)setDownloadTaskDidFinishDownloadingBlock:(nullable NSURL * _Nullable (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, NSURL *location))block;
//同上
- (void)setDownloadTaskDidWriteDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite))block;
//同上
- (void)setDownloadTaskDidResumeBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t fileOffset, int64_t expectedTotalBytes))block;
@end
///--------------------
/// @name Notifications
///--------------------
//一些通知的名稱，使用FOUNDATION_EXPORT標(biāo)識
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidResumeNotification;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidCompleteNotification;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidSuspendNotification;
FOUNDATION_EXPORT NSString * const AFURLSessionDidInvalidateNotification;
FOUNDATION_EXPORT NSString * const AFURLSessionDownloadTaskDidFailToMoveFileNotification;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidCompleteResponseDataKey;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidCompleteSerializedResponseKey;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidCompleteResponseSerializerKey;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidCompleteAssetPathKey;
FOUNDATION_EXPORT NSString * const AFNetworkingTaskDidCompleteErrorKey;
NS_ASSUME_NONNULL_END
通過頭文件可以發(fā)現(xiàn)龄捡，AFURLSessionManager是封裝了NSURLSession并實(shí)現(xiàn)了其相關(guān)的所有協(xié)議卓嫂，提供了一系列方法用于構(gòu)造各種網(wǎng)絡(luò)請求任務(wù)，并提供回調(diào)塊進(jìn)行處理聘殖，還提供了一系列設(shè)置代理方法執(zhí)行時(shí)的執(zhí)行回調(diào)塊的方法晨雳，這樣，我們也可以監(jiān)聽整個(gè)網(wǎng)絡(luò)請求的過程奸腺，當(dāng)然也可以忽略這些代理方法執(zhí)行情況餐禁，提供了各種通知，通過頭文件可以看出突照，主要目的還是為了封裝NSURLSession從而提供更加便捷的方法來實(shí)現(xiàn)網(wǎng)絡(luò)請求帮非。
接下來看一下實(shí)現(xiàn)的文件:
//C靜態(tài)函數(shù)，GCD只執(zhí)行一次，用于創(chuàng)建一個(gè)串行隊(duì)列來執(zhí)行各種網(wǎng)絡(luò)請求任務(wù)的創(chuàng)建工作
static dispatch_queue_t url_session_manager_creation_queue() {
static dispatch_queue_t af_url_session_manager_creation_queue;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
af_url_session_manager_creation_queue = dispatch_queue_create("com.alamofire.networking.session.manager.creation", DISPATCH_QUEUE_SERIAL);
});
return af_url_session_manager_creation_queue;
}
/*
C靜態(tài)函數(shù)末盔，用于執(zhí)行創(chuàng)建網(wǎng)絡(luò)請求任務(wù)的block
主要目的是為了解決ios8以下存在的一個(gè)block和task不匹配的bug
上面那個(gè)隊(duì)列也是為了解決這個(gè)bug才創(chuàng)建的
具體可查看
Open Radar:http://openradar.appspot.com/radar?id=5871104061079552 (status: Fixed in iOS8)
Issue about:https://github.com/AFNetworking/AFNetworking/issues/2093
*/
static void url_session_manager_create_task_safely(dispatch_block_t block) {
if (NSFoundationVersionNumber < NSFoundationVersionNumber_With_Fixed_5871104061079552_bug) {
dispatch_sync(url_session_manager_creation_queue(), block);
} else {
block();
}
}
//C靜態(tài)函數(shù)筑舅，創(chuàng)建一個(gè)并發(fā)隊(duì)列，用于在網(wǎng)絡(luò)請求任務(wù)完成后處理數(shù)據(jù)的陨舱，并發(fā)隊(duì)列實(shí)現(xiàn)多線程處理多個(gè)請求完成后的數(shù)據(jù)處理
static dispatch_queue_t url_session_manager_processing_queue() {
static dispatch_queue_t af_url_session_manager_processing_queue;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
af_url_session_manager_processing_queue = dispatch_queue_create("com.alamofire.networking.session.manager.processing", DISPATCH_QUEUE_CONCURRENT);
});
return af_url_session_manager_processing_queue;
}
//C靜態(tài)函數(shù)創(chuàng)建一個(gè)dispatch的組
//但在接下來的源碼中并沒有使用這個(gè)組來實(shí)現(xiàn)notify等功能翠拣，僅僅是將block和組關(guān)聯(lián)了，不太清楚具體用意
//有明白的讀者還請不吝賜教
static dispatch_group_t url_session_manager_completion_group() {
static dispatch_group_t af_url_session_manager_completion_group;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
af_url_session_manager_completion_group = dispatch_group_create();
});
return af_url_session_manager_completion_group;
}
//一系列通知名稱的定義
NSString * const AFNetworkingTaskDidResumeNotification = @"com.alamofire.networking.task.resume";
NSString * const AFNetworkingTaskDidCompleteNotification = @"com.alamofire.networking.task.complete";
NSString * const AFNetworkingTaskDidSuspendNotification = @"com.alamofire.networking.task.suspend";
NSString * const AFURLSessionDidInvalidateNotification = @"com.alamofire.networking.session.invalidate";
NSString * const AFURLSessionDownloadTaskDidFailToMoveFileNotification = @"com.alamofire.networking.session.download.file-manager-error";
NSString * const AFNetworkingTaskDidCompleteSerializedResponseKey = @"com.alamofire.networking.task.complete.serializedresponse";
NSString * const AFNetworkingTaskDidCompleteResponseSerializerKey = @"com.alamofire.networking.task.complete.responseserializer";
NSString * const AFNetworkingTaskDidCompleteResponseDataKey = @"com.alamofire.networking.complete.finish.responsedata";
NSString * const AFNetworkingTaskDidCompleteErrorKey = @"com.alamofire.networking.task.complete.error";
NSString * const AFNetworkingTaskDidCompleteAssetPathKey = @"com.alamofire.networking.task.complete.assetpath";
//需要使用的NSLock鎖的名稱
static NSString * const AFURLSessionManagerLockName = @"com.alamofire.networking.session.manager.lock";
//background session重試創(chuàng)建上傳任務(wù)次數(shù)
static NSUInteger const AFMaximumNumberOfAttemptsToRecreateBackgroundSessionUploadTask = 3;
上面的代碼定義了一系列GCD隊(duì)列游盲，根據(jù)需求有串行隊(duì)列和并行隊(duì)列误墓，串行隊(duì)列可以解決多線程情況下競爭條件的產(chǎn)生，并發(fā)隊(duì)列可以提高性能背桐，每個(gè)隊(duì)列都有自己的功能优烧，接下來會講到，接下來定義了各種通知的名稱链峭。
typedef void (^AFURLSessionDidBecomeInvalidBlock)(NSURLSession *session, NSError *error);
typedef NSURLSessionAuthChallengeDisposition (^AFURLSessionDidReceiveAuthenticationChallengeBlock)(NSURLSession *session, NSURLAuthenticationChallenge *challenge, NSURLCredential * __autoreleasing *credential);
typedef NSURLRequest * (^AFURLSessionTaskWillPerformHTTPRedirectionBlock)(NSURLSession *session, NSURLSessionTask *task, NSURLResponse *response, NSURLRequest *request);
typedef NSURLSessionAuthChallengeDisposition (^AFURLSessionTaskDidReceiveAuthenticationChallengeBlock)(NSURLSession *session, NSURLSessionTask *task, NSURLAuthenticationChallenge *challenge, NSURLCredential * __autoreleasing *credential);
typedef void (^AFURLSessionDidFinishEventsForBackgroundURLSessionBlock)(NSURLSession *session);
typedef NSInputStream * (^AFURLSessionTaskNeedNewBodyStreamBlock)(NSURLSession *session, NSURLSessionTask *task);
typedef void (^AFURLSessionTaskDidSendBodyDataBlock)(NSURLSession *session, NSURLSessionTask *task, int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend);
typedef void (^AFURLSessionTaskDidCompleteBlock)(NSURLSession *session, NSURLSessionTask *task, NSError *error);
typedef NSURLSessionResponseDisposition (^AFURLSessionDataTaskDidReceiveResponseBlock)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLResponse *response);
typedef void (^AFURLSessionDataTaskDidBecomeDownloadTaskBlock)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLSessionDownloadTask *downloadTask);
typedef void (^AFURLSessionDataTaskDidReceiveDataBlock)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSData *data);
typedef NSCachedURLResponse * (^AFURLSessionDataTaskWillCacheResponseBlock)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSCachedURLResponse *proposedResponse);
typedef NSURL * (^AFURLSessionDownloadTaskDidFinishDownloadingBlock)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, NSURL *location);
typedef void (^AFURLSessionDownloadTaskDidWriteDataBlock)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite);
typedef void (^AFURLSessionDownloadTaskDidResumeBlock)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t fileOffset, int64_t expectedTotalBytes);
typedef void (^AFURLSessionTaskProgressBlock)(NSProgress *);
typedef void (^AFURLSessionTaskCompletionHandler)(NSURLResponse *response, id responseObject, NSError *error);
上面是一系列回調(diào)塊的定義畦娄，在閱讀下面源碼的時(shí)候可以來找找看具體回調(diào)塊的參數(shù)。
//定義了一個(gè)類AFURLSessionManagerTaskDelegate并實(shí)現(xiàn)了NSURLSessionTask的相關(guān)協(xié)議
//通過名稱可以猜測弊仪，這個(gè)類是用于處理NSURLSessionTask相關(guān)代理方法的
@interface AFURLSessionManagerTaskDelegate : NSObject <NSURLSessionTaskDelegate, NSURLSessionDataDelegate, NSURLSessionDownloadDelegate>
//初始化構(gòu)造函數(shù)熙卡，需要傳入一個(gè)關(guān)聯(lián)的task
- (instancetype)initWithTask:(NSURLSessionTask *)task;
//weak修飾的manager
@property (nonatomic, weak) AFURLSessionManager *manager;
//可變data用于存儲獲取到的網(wǎng)絡(luò)數(shù)據(jù)
@property (nonatomic, strong) NSMutableData *mutableData;
//上傳進(jìn)度NSProgress
@property (nonatomic, strong) NSProgress *uploadProgress;
//下載進(jìn)度NSProgress
@property (nonatomic, strong) NSProgress *downloadProgress;
//下載文件的NSURL
@property (nonatomic, copy) NSURL *downloadFileURL;
//下載完成的回調(diào)塊
@property (nonatomic, copy) AFURLSessionDownloadTaskDidFinishDownloadingBlock downloadTaskDidFinishDownloading;
//上傳進(jìn)度的回調(diào)塊
@property (nonatomic, copy) AFURLSessionTaskProgressBlock uploadProgressBlock;
//下載進(jìn)度的回調(diào)塊
@property (nonatomic, copy) AFURLSessionTaskProgressBlock downloadProgressBlock;
//網(wǎng)絡(luò)請求完成的回調(diào)塊
@property (nonatomic, copy) AFURLSessionTaskCompletionHandler completionHandler;
@end
@implementation AFURLSessionManagerTaskDelegate
//初始化構(gòu)造函數(shù)
- (instancetype)initWithTask:(NSURLSessionTask *)task {
self = [super init];
if (!self) {
return nil;
}
_mutableData = [NSMutableData data];
_uploadProgress = [[NSProgress alloc] initWithParent:nil userInfo:nil];
_downloadProgress = [[NSProgress alloc] initWithParent:nil userInfo:nil];
//遍歷兩個(gè)上傳和下載NSProgress設(shè)置一些屬性
__weak __typeof__(task) weakTask = task;
for (NSProgress *progress in @[ _uploadProgress, _downloadProgress ])
{
//初始化progress
progress.totalUnitCount = NSURLSessionTransferSizeUnknown;
progress.cancellable = YES;
//設(shè)置取消進(jìn)度的回調(diào)塊，執(zhí)行task的cancel方法
progress.cancellationHandler = ^{
[weakTask cancel];
};
progress.pausable = YES;
//設(shè)置暫停進(jìn)度的回調(diào)塊励饵，執(zhí)行task的suspend方法
progress.pausingHandler = ^{
[weakTask suspend];
};
//設(shè)置重新開始的回調(diào)塊驳癌，執(zhí)行task的resume方法
if ([progress respondsToSelector:@selector(setResumingHandler:)]) {
progress.resumingHandler = ^{
[weakTask resume];
};
}
//progress添加kvo，監(jiān)聽progress的進(jìn)度fractionCompleted
[progress addObserver:self
forKeyPath:NSStringFromSelector(@selector(fractionCompleted))
options:NSKeyValueObservingOptionNew
context:NULL];
}
return self;
}
//析構(gòu)函數(shù)
- (void)dealloc {
//刪除KVO
[self.downloadProgress removeObserver:self forKeyPath:NSStringFromSelector(@selector(fractionCompleted))];
[self.uploadProgress removeObserver:self forKeyPath:NSStringFromSelector(@selector(fractionCompleted))];
}
#pragma mark - NSProgress Tracking
//KVO回調(diào)方法
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {
//上次或下載進(jìn)度有改變時(shí)役听，執(zhí)行上傳或下載進(jìn)度回調(diào)塊
if ([object isEqual:self.downloadProgress]) {
if (self.downloadProgressBlock) {
self.downloadProgressBlock(object);
}
}
else if ([object isEqual:self.uploadProgress]) {
if (self.uploadProgressBlock) {
self.uploadProgressBlock(object);
}
}
}
#pragma mark - NSURLSessionTaskDelegate
//代理方法颓鲜，網(wǎng)絡(luò)請求完成或出錯(cuò)
- (void)URLSession:(__unused NSURLSession *)session
task:(NSURLSessionTask *)task
didCompleteWithError:(NSError *)error
{
//manager用weak修飾，這里strong一下防止manager被釋放
__strong AFURLSessionManager *manager = self.manager;
__block id responseObject = nil;
__block NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
//為userInfo字典設(shè)置響應(yīng)序列化
userInfo[AFNetworkingTaskDidCompleteResponseSerializerKey] = manager.responseSerializer;
//Performance Improvement from #2672
//賦值mutableData到data中典予，并釋放mutableData
NSData *data = nil;
if (self.mutableData) {
data = [self.mutableData copy];
//We no longer need the reference, so nil it out to gain back some memory.
self.mutableData = nil;
}
//如果downloadFileURL存在甜滨，即是下載任務(wù)就設(shè)置下載完成后的文件存儲url到字典中
if (self.downloadFileURL) {
userInfo[AFNetworkingTaskDidCompleteAssetPathKey] = self.downloadFileURL;
} else if (data) {
//否則就設(shè)置對應(yīng)的NSData數(shù)據(jù)到字典中
userInfo[AFNetworkingTaskDidCompleteResponseDataKey] = data;
}
//如果網(wǎng)絡(luò)請求有錯(cuò)誤
if (error) {
//設(shè)置error信息到字典中
userInfo[AFNetworkingTaskDidCompleteErrorKey] = error;
/*
這個(gè)三目運(yùn)算符需要解釋一下，在其他語言中這么寫很可能就是語法錯(cuò)誤
這里的意思就是如果manager.completionGroup存在就使用它
不存在就使用url_session_manager_completion_group函數(shù)返回的group
后面的三目運(yùn)算符同理
所以如果自己不設(shè)置manager的completionGroup或completionQueue就會使用默認(rèn)提供的
*/
//執(zhí)行對應(yīng)的completionHandler回調(diào)塊
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, error);
}
//在主隊(duì)列即主線程中發(fā)送通知
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
} else {
//如果網(wǎng)絡(luò)任務(wù)成功完成瘤袖，異步在并發(fā)隊(duì)列中執(zhí)行數(shù)據(jù)處理
dispatch_async(url_session_manager_processing_queue(), ^{
//序列化響應(yīng)數(shù)據(jù)
NSError *serializationError = nil;
responseObject = [manager.responseSerializer responseObjectForResponse:task.response data:data error:&serializationError];
//如果是下載任務(wù)設(shè)置響應(yīng)數(shù)據(jù)為文件的url
if (self.downloadFileURL) {
responseObject = self.downloadFileURL;
}
//如果響應(yīng)對象序列化成功或是文件url就設(shè)置相關(guān)字典key-value
if (responseObject) {
userInfo[AFNetworkingTaskDidCompleteSerializedResponseKey] = responseObject;
}
//如果序列化出錯(cuò)衣摩，設(shè)置相關(guān)字典值
if (serializationError) {
userInfo[AFNetworkingTaskDidCompleteErrorKey] = serializationError;
}
//同理，在dispatch組中和特定隊(duì)列執(zhí)行回調(diào)塊
dispatch_group_async(manager.completionGroup ?: url_session_manager_completion_group(), manager.completionQueue ?: dispatch_get_main_queue(), ^{
if (self.completionHandler) {
self.completionHandler(task.response, responseObject, serializationError);
}
//主線程發(fā)送通知
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidCompleteNotification object:task userInfo:userInfo];
});
});
});
}
}
#pragma mark - NSURLSessionDataDelegate
//回調(diào)方法捂敌，收到數(shù)據(jù)
- (void)URLSession:(__unused NSURLSession *)session
dataTask:(__unused NSURLSessionDataTask *)dataTask
didReceiveData:(NSData *)data
{
//設(shè)置下載進(jìn)度的相關(guān)屬性
self.downloadProgress.totalUnitCount = dataTask.countOfBytesExpectedToReceive;
self.downloadProgress.completedUnitCount = dataTask.countOfBytesReceived;
//添加數(shù)據(jù)到mutableData
[self.mutableData appendData:data];
}
//上傳任務(wù)的回調(diào)方法
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didSendBodyData:(int64_t)bytesSent
totalBytesSent:(int64_t)totalBytesSent
totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend{
//設(shè)置上傳進(jìn)度的相關(guān)屬性
self.uploadProgress.totalUnitCount = task.countOfBytesExpectedToSend;
self.uploadProgress.completedUnitCount = task.countOfBytesSent;
}
#pragma mark - NSURLSessionDownloadDelegate
//下載任務(wù)的回調(diào)方法
//由于NSURLSession的downloadTask直接將文件下載到磁盤沙盒中艾扮，所以不需要mutableData自行接收數(shù)據(jù)
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didWriteData:(int64_t)bytesWritten
totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{
//設(shè)置下載進(jìn)度的相關(guān)屬性
self.downloadProgress.totalUnitCount = totalBytesExpectedToWrite;
self.downloadProgress.completedUnitCount = totalBytesWritten;
}
//恢復(fù)下載任務(wù)的回調(diào)方法
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didResumeAtOffset:(int64_t)fileOffset
expectedTotalBytes:(int64_t)expectedTotalBytes{
//設(shè)置下載進(jìn)度的相關(guān)屬性
self.downloadProgress.totalUnitCount = expectedTotalBytes;
self.downloadProgress.completedUnitCount = fileOffset;
}
//下載任務(wù)下載文件完成后的回調(diào)方法
//location就是文件下載到磁盤沙盒目錄的NSURL
- (void)URLSession:(NSURLSession *)session
downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location
{
//設(shè)置downloadFileURL為nil
self.downloadFileURL = nil;
//如果有下載完成的回調(diào)塊
if (self.downloadTaskDidFinishDownloading) {
//執(zhí)行該回調(diào)塊，這個(gè)回調(diào)塊返回一個(gè)下載的文件保存的路徑URL
//默認(rèn)保存在沙盒tmp文件中占婉，可能會被刪除泡嘴，需要持久化時(shí)要自己設(shè)置一個(gè)目錄存儲
self.downloadFileURL = self.downloadTaskDidFinishDownloading(session, downloadTask, location);
//如果需要移動文件的路徑使用NSFileManaegr移動
if (self.downloadFileURL) {
NSError *fileManagerError = nil;
if (![[NSFileManager defaultManager] moveItemAtURL:location toURL:self.downloadFileURL error:&fileManagerError]) {
//文件移動發(fā)生錯(cuò)誤發(fā)送通知
[[NSNotificationCenter defaultCenter] postNotificationName:AFURLSessionDownloadTaskDidFailToMoveFileNotification object:downloadTask userInfo:fileManagerError.userInfo];
}
}
}
}
@end
上面這個(gè)類AFURLSessionManagerTaskDelegate具體的源碼很簡單，主要就是關(guān)聯(lián)一個(gè)NSURLSessionTask并實(shí)現(xiàn)了相關(guān)任務(wù)的代理方法用于數(shù)據(jù)的獲取锐涯、上傳文件和下載文件磕诊。需要注意的是NSURLSessionTask的delegate屬性是只讀的呜师，只能在使用session創(chuàng)建task的函數(shù)中傳入代理對象胯盯，而且通過源碼也沒有發(fā)現(xiàn)相關(guān)代理的設(shè)置补憾，所以AFURLSessionManagerTaskDelegate類實(shí)現(xiàn)相關(guān)代理是為了其他類手動調(diào)用相關(guān)方法背犯，AFURLSessionManager也實(shí)現(xiàn)了這些代理翁垂，所以具體的調(diào)用是由AFURLSessionManger手動觸發(fā)的膏秫。
接下來的源碼中有一部分關(guān)于method-swizzling的技術(shù)提佣，這一部分由于篇幅問題不打算展開講解荒叼，_AFURLSessionTaskSwizzling類存在的目的就是為了交換NSURLSessionTask的resume和suspend方法的實(shí)現(xiàn)涎劈，因?yàn)?code>iOS7和iOS8中NSURLSessionTask的父類不同广凸，需要做一些處理，關(guān)于method-swizzling技術(shù)有興趣的讀者可以閱讀iOS runtime探究(四): 從runtiem開始實(shí)踐Category添加屬性與黑魔法method swizzling
接下來看一下AFURLSessionManager類的實(shí)現(xiàn)部分蛛枚。
@interface AFURLSessionManager ()
//管理的session運(yùn)行模式谅海，默認(rèn)情況下使用默認(rèn)運(yùn)行模式，defaultConfiguration
@property (readwrite, nonatomic, strong) NSURLSessionConfiguration *sessionConfiguration;
/*
NSOperation隊(duì)列蹦浦，代理方法執(zhí)行的隊(duì)列
.h文件里是readonly扭吁，所以這里定義一個(gè)readwrite用于賦值
*/
@property (readwrite, nonatomic, strong) NSOperationQueue *operationQueue;
//管理的session，readwrite
@property (readwrite, nonatomic, strong) NSURLSession *session;
//可變字典盲镶，key是NSURLSessionTask的唯一NSUInteger類型標(biāo)識侥袜，value是對應(yīng)的AFURLSessionManagerTaskDelgate對象
@property (readwrite, nonatomic, strong) NSMutableDictionary *mutableTaskDelegatesKeyedByTaskIdentifier;
//只讀屬性，通過getter返回?cái)?shù)據(jù)
@property (readonly, nonatomic, copy) NSString *taskDescriptionForSessionTasks;
//NSLock鎖
@property (readwrite, nonatomic, strong) NSLock *lock;
//下面是一系列回調(diào)塊
@property (readwrite, nonatomic, copy) AFURLSessionDidBecomeInvalidBlock sessionDidBecomeInvalid;
@property (readwrite, nonatomic, copy) AFURLSessionDidReceiveAuthenticationChallengeBlock sessionDidReceiveAuthenticationChallenge;
@property (readwrite, nonatomic, copy) AFURLSessionDidFinishEventsForBackgroundURLSessionBlock didFinishEventsForBackgroundURLSession;
@property (readwrite, nonatomic, copy) AFURLSessionTaskWillPerformHTTPRedirectionBlock taskWillPerformHTTPRedirection;
@property (readwrite, nonatomic, copy) AFURLSessionTaskDidReceiveAuthenticationChallengeBlock taskDidReceiveAuthenticationChallenge;
@property (readwrite, nonatomic, copy) AFURLSessionTaskNeedNewBodyStreamBlock taskNeedNewBodyStream;
@property (readwrite, nonatomic, copy) AFURLSessionTaskDidSendBodyDataBlock taskDidSendBodyData;
@property (readwrite, nonatomic, copy) AFURLSessionTaskDidCompleteBlock taskDidComplete;
@property (readwrite, nonatomic, copy) AFURLSessionDataTaskDidReceiveResponseBlock dataTaskDidReceiveResponse;
@property (readwrite, nonatomic, copy) AFURLSessionDataTaskDidBecomeDownloadTaskBlock dataTaskDidBecomeDownloadTask;
@property (readwrite, nonatomic, copy) AFURLSessionDataTaskDidReceiveDataBlock dataTaskDidReceiveData;
@property (readwrite, nonatomic, copy) AFURLSessionDataTaskWillCacheResponseBlock dataTaskWillCacheResponse;
@property (readwrite, nonatomic, copy) AFURLSessionDownloadTaskDidFinishDownloadingBlock downloadTaskDidFinishDownloading;
@property (readwrite, nonatomic, copy) AFURLSessionDownloadTaskDidWriteDataBlock downloadTaskDidWriteData;
@property (readwrite, nonatomic, copy) AFURLSessionDownloadTaskDidResumeBlock downloadTaskDidResume;
@end
上面就是定義了一系列的回調(diào)塊和一些屬性溉贿。
@implementation AFURLSessionManager
//構(gòu)造函數(shù)
- (instancetype)init {
return [self initWithSessionConfiguration:nil];
}
//構(gòu)造函數(shù)
- (instancetype)initWithSessionConfiguration:(NSURLSessionConfiguration *)configuration {
self = [super init];
if (!self) {
return nil;
}
//如果沒有指定session運(yùn)行模式就使用默認(rèn)的
if (!configuration) {
configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
}
self.sessionConfiguration = configuration;
//創(chuàng)建代理方法執(zhí)行的隊(duì)列枫吧，最大并發(fā)數(shù)為1，即串行隊(duì)列
self.operationQueue = [[NSOperationQueue alloc] init];
self.operationQueue.maxConcurrentOperationCount = 1;
//創(chuàng)建session宇色，注意代理對象是self
self.session = [NSURLSession sessionWithConfiguration:self.sessionConfiguration delegate:self delegateQueue:self.operationQueue];
//創(chuàng)建響應(yīng)序列化器
self.responseSerializer = [AFJSONResponseSerializer serializer];
//設(shè)置默認(rèn)安全策略
self.securityPolicy = [AFSecurityPolicy defaultPolicy];
#if !TARGET_OS_WATCH
//獲取網(wǎng)絡(luò)可達(dá)性manager
self.reachabilityManager = [AFNetworkReachabilityManager sharedManager];
#endif
self.mutableTaskDelegatesKeyedByTaskIdentifier = [[NSMutableDictionary alloc] init];
//創(chuàng)建鎖
self.lock = [[NSLock alloc] init];
self.lock.name = AFURLSessionManagerLockName;
/*
獲取session中的任務(wù)九杂，并調(diào)用相關(guān)方法關(guān)聯(lián)AFURLSessionManagerTaskDelegate
不太明白這里為什么要這么做，剛創(chuàng)建的session應(yīng)該沒有任何任務(wù)在執(zhí)行
*/
[self.session getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) {
for (NSURLSessionDataTask *task in dataTasks) {
[self addDelegateForDataTask:task uploadProgress:nil downloadProgress:nil completionHandler:nil];
}
for (NSURLSessionUploadTask *uploadTask in uploadTasks) {
[self addDelegateForUploadTask:uploadTask progress:nil completionHandler:nil];
}
for (NSURLSessionDownloadTask *downloadTask in downloadTasks) {
[self addDelegateForDownloadTask:downloadTask progress:nil destination:nil completionHandler:nil];
}
}];
return self;
}
//析構(gòu)方法宣蠕，移除所有通知監(jiān)聽
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
初始化方法中不太理解的地方就是在創(chuàng)建完session后就去獲取它正在執(zhí)行的相關(guān)任務(wù)例隆，但是剛創(chuàng)建的session為什么會存在正在執(zhí)行的任務(wù)呢？如果有讀者明白還請不吝賜教植影。
//taskDescriptionForSessionTasks屬性的getter裳擎，返回地址的字符串形式數(shù)據(jù)，可以保證這個(gè)字符串是唯一的
- (NSString *)taskDescriptionForSessionTasks {
return [NSString stringWithFormat:@"%p", self];
}
//通知的回調(diào)方法思币，接下來的代碼會添加相關(guān)通知
- (void)taskDidResume:(NSNotification *)notification {
//發(fā)送通知的時(shí)候會將task添加進(jìn)通知中
NSURLSessionTask *task = notification.object;
//判斷這個(gè)任務(wù)是否是當(dāng)前manager管理的鹿响，如果是就發(fā)送相關(guān)通知
//task的taskDescription屬性在下文的源碼中會設(shè)置
if ([task respondsToSelector:@selector(taskDescription)]) {
if ([task.taskDescription isEqualToString:self.taskDescriptionForSessionTasks]) {
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidResumeNotification object:task];
});
}
}
}
//同上
- (void)taskDidSuspend:(NSNotification *)notification {
NSURLSessionTask *task = notification.object;
if ([task respondsToSelector:@selector(taskDescription)]) {
if ([task.taskDescription isEqualToString:self.taskDescriptionForSessionTasks]) {
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:AFNetworkingTaskDidSuspendNotification object:task];
});
}
}
}
上面的代碼就是通知的回調(diào)方法，用于通知resume和suspend事件谷饿。
//根據(jù)task獲取相關(guān)聯(lián)的AFURLSessionManagerTaskDelegate對象
- (AFURLSessionManagerTaskDelegate *)delegateForTask:(NSURLSessionTask *)task {
//task不能為空
NSParameterAssert(task);
//上鎖惶我，通過task的唯一taskIdentifier從字典中取值，這個(gè)唯一標(biāo)識是在創(chuàng)建task的時(shí)候NSURLSessionTask為其設(shè)置的博投，不需要手動設(shè)置绸贡，保證唯一性
AFURLSessionManagerTaskDelegate *delegate = nil;
[self.lock lock];
delegate = self.mutableTaskDelegatesKeyedByTaskIdentifier[@(task.taskIdentifier)];
[self.lock unlock];
return delegate;
}
//為task設(shè)置關(guān)聯(lián)的delegate
- (void)setDelegate:(AFURLSessionManagerTaskDelegate *)delegate
forTask:(NSURLSessionTask *)task
{
//task和delegate都不能為空
NSParameterAssert(task);
NSParameterAssert(delegate);
//上鎖，向字典中添加key-value對
[self.lock lock];
self.mutableTaskDelegatesKeyedByTaskIdentifier[@(task.taskIdentifier)] = delegate;
[self addNotificationObserverForTask:task];
[self.lock unlock];
}
//重點(diǎn)方法，為dataTask創(chuàng)建一個(gè)關(guān)聯(lián)的AFURLSessionManagerTaskDelegate對象
- (void)addDelegateForDataTask:(NSURLSessionDataTask *)dataTask
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
//創(chuàng)建AFURLSessionManagerTaskDelegate
AFURLSessionManagerTaskDelegate *delegate = [[AFURLSessionManagerTaskDelegate alloc] initWithTask:dataTask];
//設(shè)置相關(guān)屬性
delegate.manager = self;
delegate.completionHandler = completionHandler;
/*
設(shè)置task的taskDescription听怕，注意和taskIdentifier區(qū)分
taskDescription是開發(fā)者自行設(shè)置的
taskIdentifier是NSURLSessionTask設(shè)置的捧挺，保證每一個(gè)task的id不同
這里設(shè)置的taskDescription就是AFURLSessionManager的地址
所以同一個(gè)manager創(chuàng)建的task的description都是一致的
設(shè)置這個(gè)值的目的就是為了區(qū)分task是否是當(dāng)前manger創(chuàng)建的
*/
dataTask.taskDescription = self.taskDescriptionForSessionTasks;
//調(diào)用上面的方法將task-delegate鍵值對添加進(jìn)字典中
[self setDelegate:delegate forTask:dataTask];
//設(shè)置回調(diào)塊
delegate.uploadProgressBlock = uploadProgressBlock;
delegate.downloadProgressBlock = downloadProgressBlock;
}
//同上，創(chuàng)建上傳任務(wù)的AFURLSessionManagerTaskDelegate對象尿瞭，并加入到字典中
- (void)addDelegateForUploadTask:(NSURLSessionUploadTask *)uploadTask
progress:(void (^)(NSProgress *uploadProgress)) uploadProgressBlock
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
AFURLSessionManagerTaskDelegate *delegate = [[AFURLSessionManagerTaskDelegate alloc] initWithTask:uploadTask];
delegate.manager = self;
delegate.completionHandler = completionHandler;
uploadTask.taskDescription = self.taskDescriptionForSessionTasks;
[self setDelegate:delegate forTask:uploadTask];
delegate.uploadProgressBlock = uploadProgressBlock;
}
//同上闽烙，創(chuàng)建下載文件任務(wù)的AFURLSessionManagerTaskDelegate對象，并加入到字典中
- (void)addDelegateForDownloadTask:(NSURLSessionDownloadTask *)downloadTask
progress:(void (^)(NSProgress *downloadProgress)) downloadProgressBlock
destination:(NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(void (^)(NSURLResponse *response, NSURL *filePath, NSError *error))completionHandler
{
AFURLSessionManagerTaskDelegate *delegate = [[AFURLSessionManagerTaskDelegate alloc] initWithTask:downloadTask];
delegate.manager = self;
delegate.completionHandler = completionHandler;
/*
需要注意下声搁，AFURLSessionManagerTaskDelegate中下載文件完成后會調(diào)用delegate.downloadTaskDidFinishDownloading回調(diào)塊
來獲取下載文件要移動到的目錄URL
所以這里就是創(chuàng)建這個(gè)回調(diào)塊黑竞，直接返回參數(shù)中的destination回調(diào)塊
*/
if (destination) {
delegate.downloadTaskDidFinishDownloading = ^NSURL * (NSURLSession * __unused session, NSURLSessionDownloadTask *task, NSURL *location) {
return destination(location, task.response);
};
}
downloadTask.taskDescription = self.taskDescriptionForSessionTasks;
[self setDelegate:delegate forTask:downloadTask];
delegate.downloadProgressBlock = downloadProgressBlock;
}
//從字典中刪除task對應(yīng)的delegate的key-value對
- (void)removeDelegateForTask:(NSURLSessionTask *)task {
NSParameterAssert(task);
[self.lock lock];
[self removeNotificationObserverForTask:task];
[self.mutableTaskDelegatesKeyedByTaskIdentifier removeObjectForKey:@(task.taskIdentifier)];
[self.lock unlock];
}
上面的代碼就是對AFURLSessionManagerTaskDelegate的創(chuàng)建、添加進(jìn)字典疏旨、刪除很魂、獲取的操作，這樣就實(shí)現(xiàn)了每一個(gè)NSURLSessionTask對應(yīng)一個(gè)AFURLSessionManagerTaskDelegate對象檐涝，可能讀者會有疑問遏匆，AFURLSessionManager既然已經(jīng)實(shí)現(xiàn)了代理的方法，為什么不直接使用它來處理代理方法骤铃，為什么要?jiǎng)?chuàng)建一個(gè)類來專門處理拉岁，繼續(xù)看完源碼可能你就會明白了。
//根據(jù)keyPath獲取不同類型任務(wù)的集合
- (NSArray *)tasksForKeyPath:(NSString *)keyPath {
__block NSArray *tasks = nil;
//創(chuàng)建一個(gè)信號量惰爬，值是0
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
//這個(gè)方法是異步的喊暖，所以為了同步返回結(jié)果，需要使用鎖撕瞧，信號量值設(shè)置為0或者1時(shí)就可以當(dāng)鎖來使用了
[self.session getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) {
if ([keyPath isEqualToString:NSStringFromSelector(@selector(dataTasks))]) {
tasks = dataTasks;
} else if ([keyPath isEqualToString:NSStringFromSelector(@selector(uploadTasks))]) {
tasks = uploadTasks;
} else if ([keyPath isEqualToString:NSStringFromSelector(@selector(downloadTasks))]) {
tasks = downloadTasks;
} else if ([keyPath isEqualToString:NSStringFromSelector(@selector(tasks))]) {
tasks = [@[dataTasks, uploadTasks, downloadTasks] valueForKeyPath:@"@unionOfArrays.self"];
}
//signal通知信號量陵叽，信號量值加1
dispatch_semaphore_signal(semaphore);
}];
//等待信號量，直到值大于0丛版，等待時(shí)間是forever
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
return tasks;
}
//下面是tasks巩掺、dataTasks、uploadTasks页畦、downloadTasks屬性的getter胖替，都是調(diào)用上述方法來獲取對應(yīng)類型的任務(wù)集合
- (NSArray *)tasks {
return [self tasksForKeyPath:NSStringFromSelector(_cmd)];
}
- (NSArray *)dataTasks {
return [self tasksForKeyPath:NSStringFromSelector(_cmd)];
}
- (NSArray *)uploadTasks {
return [self tasksForKeyPath:NSStringFromSelector(_cmd)];
}
- (NSArray *)downloadTasks {
return [self tasksForKeyPath:NSStringFromSelector(_cmd)];
}
#pragma mark -
//設(shè)置session無效，根據(jù)參數(shù)判斷是否需要取消正在執(zhí)行的任務(wù)
- (void)invalidateSessionCancelingTasks:(BOOL)cancelPendingTasks {
//調(diào)用NSURLSession對應(yīng)的方法來設(shè)置session無效豫缨，同時(shí)打破引用循環(huán)
if (cancelPendingTasks) {
[self.session invalidateAndCancel];
} else {
[self.session finishTasksAndInvalidate];
}
}
#pragma mark -
//responseSerializer的setter
- (void)setResponseSerializer:(id <AFURLResponseSerialization>)responseSerializer {
NSParameterAssert(responseSerializer);
_responseSerializer = responseSerializer;
}
#pragma mark -
//添加通知独令，taskDidResume、taskDidSuspend方法前面講過了
- (void)addNotificationObserverForTask:(NSURLSessionTask *)task {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(taskDidResume:) name:AFNSURLSessionTaskDidResumeNotification object:task];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(taskDidSuspend:) name:AFNSURLSessionTaskDidSuspendNotification object:task];
}
//刪除通知
- (void)removeNotificationObserverForTask:(NSURLSessionTask *)task {
[[NSNotificationCenter defaultCenter] removeObserver:self name:AFNSURLSessionTaskDidSuspendNotification object:task];
[[NSNotificationCenter defaultCenter] removeObserver:self name:AFNSURLSessionTaskDidResumeNotification object:task];
}
上面的方法是一些getter和setter好芭，很簡單燃箭，不再贅述。
//創(chuàng)建并返回NSURLSessionDataTask
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
return [self dataTaskWithRequest:request uploadProgress:nil downloadProgress:nil completionHandler:completionHandler];
}
//創(chuàng)建并返回NSURLSessionDataTask
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
uploadProgress:(nullable void (^)(NSProgress *uploadProgress)) uploadProgressBlock
downloadProgress:(nullable void (^)(NSProgress *downloadProgress)) downloadProgressBlock
completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler {
//為了解決iOS8一下的一個(gè)bug舍败，調(diào)用一個(gè)串行隊(duì)列來創(chuàng)建dataTask
__block NSURLSessionDataTask *dataTask = nil;
url_session_manager_create_task_safely(^{
//使用session來創(chuàng)建一個(gè)NSURLSessionDataTask對象
dataTask = [self.session dataTaskWithRequest:request];
});
//為這個(gè)task創(chuàng)建一個(gè)AFURLSessionManagerTaskDelegate并關(guān)聯(lián)加入字典中
[self addDelegateForDataTask:dataTask uploadProgress:uploadProgressBlock downloadProgress:downloadProgressBlock completionHandler:completionHandler];
return dataTask;
}
#pragma mark -
//創(chuàng)建一個(gè)NSURLSessionUploadTask對象
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
fromFile:(NSURL *)fileURL
progress:(void (^)(NSProgress *uploadProgress)) uploadProgressBlock
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
__block NSURLSessionUploadTask *uploadTask = nil;
url_session_manager_create_task_safely(^{
uploadTask = [self.session uploadTaskWithRequest:request fromFile:fileURL];
});
// uploadTask may be nil on iOS7 because uploadTaskWithRequest:fromFile: may return nil despite being documented as nonnull (https://devforums.apple.com/message/926113#926113)
//解決iOS7的一個(gè)bug按照配置的嘗試次數(shù)創(chuàng)建上傳任務(wù)招狸，默認(rèn)嘗試3次
if (!uploadTask && self.attemptsToRecreateUploadTasksForBackgroundSessions && self.session.configuration.identifier) {
for (NSUInteger attempts = 0; !uploadTask && attempts < AFMaximumNumberOfAttemptsToRecreateBackgroundSessionUploadTask; attempts++) {
uploadTask = [self.session uploadTaskWithRequest:request fromFile:fileURL];
}
}
//創(chuàng)建關(guān)聯(lián)的delegate并添加到字典中
[self addDelegateForUploadTask:uploadTask progress:uploadProgressBlock completionHandler:completionHandler];
return uploadTask;
}
//同上
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
fromData:(NSData *)bodyData
progress:(void (^)(NSProgress *uploadProgress)) uploadProgressBlock
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
__block NSURLSessionUploadTask *uploadTask = nil;
url_session_manager_create_task_safely(^{
uploadTask = [self.session uploadTaskWithRequest:request fromData:bodyData];
});
[self addDelegateForUploadTask:uploadTask progress:uploadProgressBlock completionHandler:completionHandler];
return uploadTask;
}
//同上
- (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request
progress:(void (^)(NSProgress *uploadProgress)) uploadProgressBlock
completionHandler:(void (^)(NSURLResponse *response, id responseObject, NSError *error))completionHandler
{
__block NSURLSessionUploadTask *uploadTask = nil;
url_session_manager_create_task_safely(^{
uploadTask = [self.session uploadTaskWithStreamedRequest:request];
});
[self addDelegateForUploadTask:uploadTask progress:uploadProgressBlock completionHandler:completionHandler];
return uploadTask;
}
#pragma mark -
//創(chuàng)建下載任務(wù)敬拓，同上
- (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request
progress:(void (^)(NSProgress *downloadProgress)) downloadProgressBlock
destination:(NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(void (^)(NSURLResponse *response, NSURL *filePath, NSError *error))completionHandler
{
__block NSURLSessionDownloadTask *downloadTask = nil;
url_session_manager_create_task_safely(^{
downloadTask = [self.session downloadTaskWithRequest:request];
});
[self addDelegateForDownloadTask:downloadTask progress:downloadProgressBlock destination:destination completionHandler:completionHandler];
return downloadTask;
}
//創(chuàng)建下載任務(wù)，同上
- (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData
progress:(void (^)(NSProgress *downloadProgress)) downloadProgressBlock
destination:(NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
completionHandler:(void (^)(NSURLResponse *response, NSURL *filePath, NSError *error))completionHandler
{
__block NSURLSessionDownloadTask *downloadTask = nil;
url_session_manager_create_task_safely(^{
downloadTask = [self.session downloadTaskWithResumeData:resumeData];
});
[self addDelegateForDownloadTask:downloadTask progress:downloadProgressBlock destination:destination completionHandler:completionHandler];
return downloadTask;
}
上面的方法就是AFURLSessionManager為我們提供的獲取NSURLSessionDataTask裙戏、NSURLSessionUploadTask和NSURLSessionDownloadTask的方法乘凸，上面這些方法主要目的就是傳入進(jìn)度或完成回調(diào)塊，然后構(gòu)造一個(gè)AFURLSessionManagerTaskDeleagte對象并關(guān)聯(lián)挽懦，這樣就不需要開發(fā)者自行實(shí)現(xiàn)和管理代理方法做相關(guān)數(shù)據(jù)處理翰意，只需要在回調(diào)塊中做處理即可木人。
接下來源碼中是一系列回調(diào)塊的setter方法信柿，就不列下來了，讀者可以自己看看醒第。接下來就講解重點(diǎn)的各種代理的回調(diào)方法渔嚷。
//session無效后的回調(diào)方法
- (void)URLSession:(NSURLSession *)session
didBecomeInvalidWithError:(NSError *)error
{
//如果回調(diào)塊存在就執(zhí)行回調(diào)塊
if (self.sessionDidBecomeInvalid) {
self.sessionDidBecomeInvalid(session, error);
}
//發(fā)送對應(yīng)通知
[[NSNotificationCenter defaultCenter] postNotificationName:AFURLSessionDidInvalidateNotification object:session];
}
//收到服務(wù)端的challenge，例如https需要驗(yàn)證證書等
- (void)URLSession:(NSURLSession *)session
didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler
{
NSURLSessionAuthChallengeDisposition disposition = NSURLSessionAuthChallengePerformDefaultHandling;
__block NSURLCredential *credential = nil;
//如果有對應(yīng)回調(diào)塊就執(zhí)行
if (self.sessionDidReceiveAuthenticationChallenge) {
disposition = self.sessionDidReceiveAuthenticationChallenge(session, challenge, &credential);
} else {
//處理https
if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
if ([self.securityPolicy evaluateServerTrust:challenge.protectionSpace.serverTrust forDomain:challenge.protectionSpace.host]) {
credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
if (credential) {
disposition = NSURLSessionAuthChallengeUseCredential;
} else {
disposition = NSURLSessionAuthChallengePerformDefaultHandling;
}
} else {
disposition = NSURLSessionAuthChallengeCancelAuthenticationChallenge;
}
} else {
disposition = NSURLSessionAuthChallengePerformDefaultHandling;
}
}
if (completionHandler) {
completionHandler(disposition, credential);
}
}
上面兩個(gè)方法是NSURLSessionDelegate的方法稠曼，關(guān)于驗(yàn)證HTTPS的部分代碼可以當(dāng)做模板代碼來寫形病，具體內(nèi)容不是本文講解范疇，讀者可自行查閱霞幅。
//要執(zhí)行重定向的代理方法
- (void)URLSession:(NSURLSession *)session
task:(NSURLSessionTask *)task
willPerformHTTPRedirection:(NSHTTPURLResponse *)response
newRequest:(NSURLRequest *)request
completionHandler:(void (^)(NSURLRequest *))completionHandler
{
//套路就是執(zhí)行用戶自定義的回調(diào)塊漠吻，執(zhí)行完成回調(diào)塊
NSURLRequest *redirectRequest = request;
if (self.taskWillPerformHTTPRedirection) {
redirectRequest = self.taskWillPerformHTTPRedirection(session, task, response, request);
}
if (completionHandler) {
completionHandler(redirectRequest);
}
}
//同前面一樣，處理https鏈接
- (void)URLSession:(NSURLSession *)session
task:(NSURLSessionTask *)task
didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler
{
NSURLSessionAuthChallengeDisposition disposition = NSURLSessionAuthChallengePerformDefaultHandling;
__block NSURLCredential *credential = nil;
if (self.taskDidReceiveAuthenticationChallenge) {
disposition = self.taskDidReceiveAuthenticationChallenge(session, task, challenge, &credential);
} else {
if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
if ([self.securityPolicy evaluateServerTrust:challenge.protectionSpace.serverTrust forDomain:challenge.protectionSpace.host]) {
disposition = NSURLSessionAuthChallengeUseCredential;
credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
} else {
disposition = NSURLSessionAuthChallengeCancelAuthenticationChallenge;
}
} else {
disposition = NSURLSessionAuthChallengePerformDefaultHandling;
}
}
if (completionHandler) {
completionHandler(disposition, credential);
}
}
//處理需要一個(gè)新的流
- (void)URLSession:(NSURLSession *)session
task:(NSURLSessionTask *)task
needNewBodyStream:(void (^)(NSInputStream *bodyStream))completionHandler
{
//調(diào)用用戶自定義的回調(diào)塊來獲取司恳，或者copy一個(gè)
NSInputStream *inputStream = nil;
if (self.taskNeedNewBodyStream) {
inputStream = self.taskNeedNewBodyStream(session, task);
} else if (task.originalRequest.HTTPBodyStream && [task.originalRequest.HTTPBodyStream conformsToProtocol:@protocol(NSCopying)]) {
inputStream = [task.originalRequest.HTTPBodyStream copy];
}
if (completionHandler) {
completionHandler(inputStream);
}
}
//上傳任務(wù)的回調(diào)方法
- (void)URLSession:(NSURLSession *)session
task:(NSURLSessionTask *)task
didSendBodyData:(int64_t)bytesSent
totalBytesSent:(int64_t)totalBytesSent
totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend
{
//獲取上傳的總大小途乃，如果數(shù)據(jù)不正確就從http首部中獲取
int64_t totalUnitCount = totalBytesExpectedToSend;
if(totalUnitCount == NSURLSessionTransferSizeUnknown) {
NSString *contentLength = [task.originalRequest valueForHTTPHeaderField:@"Content-Length"];
if(contentLength) {
totalUnitCount = (int64_t) [contentLength longLongValue];
}
}
//獲取task關(guān)聯(lián)的AFURLSessionManagerTaskDelegate對象
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:task];
//如果代理對象存在，就調(diào)用代理對象的這個(gè)方法
if (delegate) {
[delegate URLSession:session task:task didSendBodyData:bytesSent totalBytesSent:totalBytesSent totalBytesExpectedToSend:totalBytesExpectedToSend];
}
//如果用戶自定義回調(diào)塊存在扔傅，執(zhí)行回調(diào)塊
if (self.taskDidSendBodyData) {
self.taskDidSendBodyData(session, task, bytesSent, totalBytesSent, totalUnitCount);
}
}
//任務(wù)完成的回調(diào)方法
- (void)URLSession:(NSURLSession *)session
task:(NSURLSessionTask *)task
didCompleteWithError:(NSError *)error
{
//同樣的套路耍共，獲取關(guān)聯(lián)的代理對象，手動調(diào)用代理對象的這個(gè)方法猎塞，執(zhí)行用戶自定義的回調(diào)塊
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:task];
// delegate may be nil when completing a task in the background
if (delegate) {
[delegate URLSession:session task:task didCompleteWithError:error];
[self removeDelegateForTask:task];
}
if (self.taskDidComplete) {
self.taskDidComplete(session, task, error);
}
}
以上代碼是NSURLSessionTaskDelegate的回調(diào)方法试读，通過上面的代碼可以發(fā)現(xiàn)AFURLSessionManagerTaskDelegate的作用了，AFURLSessionManager的代理方法中會根據(jù)task獲取到對應(yīng)的delegate荠耽，如果需要提前處理一些數(shù)據(jù)就先處理钩骇，處理完成后手動觸發(fā)delegate中的對應(yīng)方法，然后具體的數(shù)據(jù)處理就交由AFURLSessionManagerTaskDelegate來處理铝量。繼續(xù)看其他代理方法:
//收到服務(wù)端響應(yīng)的代理回調(diào)方法
- (void)URLSession:(NSURLSession *)session
dataTask:(NSURLSessionDataTask *)dataTask
didReceiveResponse:(NSURLResponse *)response
completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler
{
//調(diào)用用戶自定義回調(diào)塊倘屹，執(zhí)行完成回調(diào)塊
NSURLSessionResponseDisposition disposition = NSURLSessionResponseAllow;
if (self.dataTaskDidReceiveResponse) {
disposition = self.dataTaskDidReceiveResponse(session, dataTask, response);
}
if (completionHandler) {
completionHandler(disposition);
}
}
- (void)URLSession:(NSURLSession *)session
dataTask:(NSURLSessionDataTask *)dataTask
didBecomeDownloadTask:(NSURLSessionDownloadTask *)downloadTask
{
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:dataTask];
if (delegate) {
[self removeDelegateForTask:dataTask];
[self setDelegate:delegate forTask:downloadTask];
}
if (self.dataTaskDidBecomeDownloadTask) {
self.dataTaskDidBecomeDownloadTask(session, dataTask, downloadTask);
}
}
- (void)URLSession:(NSURLSession *)session
dataTask:(NSURLSessionDataTask *)dataTask
didReceiveData:(NSData *)data
{
//獲取代理，然后調(diào)用代理的這個(gè)方法款违，有自定義回調(diào)塊就執(zhí)行
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:dataTask];
[delegate URLSession:session dataTask:dataTask didReceiveData:data];
if (self.dataTaskDidReceiveData) {
self.dataTaskDidReceiveData(session, dataTask, data);
}
}
- (void)URLSession:(NSURLSession *)session
dataTask:(NSURLSessionDataTask *)dataTask
willCacheResponse:(NSCachedURLResponse *)proposedResponse
completionHandler:(void (^)(NSCachedURLResponse *cachedResponse))completionHandler
{
NSCachedURLResponse *cachedResponse = proposedResponse;
if (self.dataTaskWillCacheResponse) {
cachedResponse = self.dataTaskWillCacheResponse(session, dataTask, proposedResponse);
}
if (completionHandler) {
completionHandler(cachedResponse);
}
}
- (void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session {
if (self.didFinishEventsForBackgroundURLSession) {
dispatch_async(dispatch_get_main_queue(), ^{
self.didFinishEventsForBackgroundURLSession(session);
});
}
}
上面的代碼是NSURLSessionDataDelegate的代理方法唐瀑，同樣的，如果AFURLSessionManagerTaskDelegate能響應(yīng)的關(guān)于數(shù)據(jù)處理的方法都會通過task找到對應(yīng)delegate后調(diào)用其對應(yīng)的方法插爹，然后執(zhí)行用戶自定義的回調(diào)塊哄辣，如果代理不能響應(yīng)的方法就由AFURLSessionManager自行處理请梢。
//下載任務(wù)下載文件完成后的回調(diào)方法
- (void)URLSession:(NSURLSession *)session
downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location
{
//獲取對應(yīng)的代理對象
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:downloadTask];
//如果downloadTaskDidFinishDownloading回調(diào)塊存在就執(zhí)行它來獲取一個(gè)保存文件的URL路徑
if (self.downloadTaskDidFinishDownloading) {
NSURL *fileURL = self.downloadTaskDidFinishDownloading(session, downloadTask, location);
//如果這個(gè)路徑存在就通過NSFileManager來移動，移動失敗發(fā)送通知
if (fileURL) {
delegate.downloadFileURL = fileURL;
NSError *error = nil;
if (![[NSFileManager defaultManager] moveItemAtURL:location toURL:fileURL error:&error]) {
[[NSNotificationCenter defaultCenter] postNotificationName:AFURLSessionDownloadTaskDidFailToMoveFileNotification object:downloadTask userInfo:error.userInfo];
}
return;
}
}
if (delegate) {
[delegate URLSession:session downloadTask:downloadTask didFinishDownloadingToURL:location];
}
}
- (void)URLSession:(NSURLSession *)session
downloadTask:(NSURLSessionDownloadTask *)downloadTask
didWriteData:(int64_t)bytesWritten
totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
//通過task獲取delegate
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:downloadTask];
//如果delegate存在就調(diào)用其該方法
if (delegate) {
[delegate URLSession:session downloadTask:downloadTask didWriteData:bytesWritten totalBytesWritten:totalBytesWritten totalBytesExpectedToWrite:totalBytesExpectedToWrite];
}
//如果回調(diào)塊存在就執(zhí)行
if (self.downloadTaskDidWriteData) {
self.downloadTaskDidWriteData(session, downloadTask, bytesWritten, totalBytesWritten, totalBytesExpectedToWrite);
}
}
//同上套路
- (void)URLSession:(NSURLSession *)session
downloadTask:(NSURLSessionDownloadTask *)downloadTask
didResumeAtOffset:(int64_t)fileOffset
expectedTotalBytes:(int64_t)expectedTotalBytes
{
AFURLSessionManagerTaskDelegate *delegate = [self delegateForTask:downloadTask];
if (delegate) {
[delegate URLSession:session downloadTask:downloadTask didResumeAtOffset:fileOffset expectedTotalBytes:expectedTotalBytes];
}
if (self.downloadTaskDidResume) {
self.downloadTaskDidResume(session, downloadTask, fileOffset, expectedTotalBytes);
}
}
到現(xiàn)在為止力穗，AFURLSessionManager所有源碼都看完了毅弧，代碼封裝了NSURLSession并提供了簡潔的創(chuàng)建NSURLSessionDataTask、NSURLSessionUploadTask和NSURLSessionDownloadTask對象的方法当窗，使用人員可以不需要考慮具體的數(shù)據(jù)處理過程够坐，最簡單的可以只通過回調(diào)塊來獲取網(wǎng)絡(luò)請求的各種信息。在具體實(shí)現(xiàn)上崖面，AFURLSessionManager通過定義AFURLSessionManagerTaskDelegate來做具體task的數(shù)據(jù)處理元咙，而AFURLSessionManager只關(guān)注于通用部分的實(shí)現(xiàn)，并提供各種方法和回調(diào)塊用于處理task巫员，使得代碼結(jié)構(gòu)更清晰庶香，AFURLSessionManager代理方法結(jié)構(gòu)也更簡單。
通過源碼閱讀也可以學(xué)到AFURLSessionManager是如何使用和管理NSURLSession简识，以及相關(guān)回調(diào)方法具體實(shí)現(xiàn)細(xì)節(jié)赶掖，使用一個(gè)類就封裝了三種任務(wù)的處理方法，所以可以很便捷的使用七扰，在開發(fā)中我們經(jīng)常使用AFHTTPSessionManager奢赂，其是AFURLSessionManager的子類，所以颈走，閱讀完AFURLSessionManager源碼后膳灶，我們可以直接使用AFURLSessionManager就能很方便的進(jìn)行網(wǎng)絡(luò)請求，舉個(gè)栗子如下:
- (void)viewWillAppear:(BOOL)animated
{
//創(chuàng)建一個(gè)AFURLSessionManager對象疫鹊，其中管理的session運(yùn)行在默認(rèn)模式下
AFURLSessionManager *manager = [[AFURLSessionManager alloc] init];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"https://www.baidu.com"]];
//獲取一個(gè)NSURLSessionDataTask對象袖瞻，訪問百度
NSURLSessionDataTask *task = [manager dataTaskWithRequest:request completionHandler:^(NSURLResponse * _Nonnull response, id _Nullable responseObject, NSError * _Nullable error) {
//請求完成后的回調(diào)
NSLog(@"receive %@ %@ %@", response, responseObject, error);
}];
//啟動任務(wù)
[task resume];
//創(chuàng)建一個(gè)下載tomcat的request
NSURLRequest *downloadRequest = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://mirrors.tuna.tsinghua.edu.cn/apache/tomcat/tomcat-9/v9.0.1/bin/apache-tomcat-9.0.1.zip"]];
//創(chuàng)建一個(gè)下載任務(wù)
NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:downloadRequest progress:^(NSProgress * _Nonnull downloadProgress) {
//每下載一包數(shù)據(jù)就輸出一下完成情況
NSLog(@"Download %lf", downloadProgress.fractionCompleted);
} destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
//演示代碼不需要存儲在磁盤中，返回nil拆吆，如有需要自行指定目錄
return nil;
} completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
//完成后輸出相關(guān)信息
NSLog(@"Download Complete %@ %@ %@", response, filePath, error);
}];
//啟動下載任務(wù)
[downloadTask resume];
}
上面的栗子很簡單聋迎，就不再贅述了，有興趣的讀者可以打斷點(diǎn)看一下執(zhí)行過程是不是如源碼中講解的那般枣耀。
備注
由于作者水平有限霉晕，難免出現(xiàn)紕漏，如有問題還請不吝賜教捞奕。
