版本記錄
| 版本號(hào) | 時(shí)間 |
|---|---|
| V1.0 | 2018.03.05 |
前言
我們做APP發(fā)起網(wǎng)絡(luò)請(qǐng)求暮芭，都離不開一個(gè)非常有用的框架AFNetworking，可以說這個(gè)框架的知名度已經(jīng)超過了蘋果的底層網(wǎng)絡(luò)請(qǐng)求部分欲低，很多人可能不知道蘋果底層是如何發(fā)起網(wǎng)絡(luò)請(qǐng)求的辕宏，但是一定知道
AFNetworking，接下來幾篇我們就一起詳細(xì)的解析一下這個(gè)框架砾莱。感興趣的可以看上面寫的幾篇瑞筐。
1. AFNetworking源碼探究（一） —— 基本介紹
2. AFNetworking源碼探究（二） —— GET請(qǐng)求實(shí)現(xiàn)之NSURLSessionDataTask實(shí)例化（一）
3. AFNetworking源碼探究（三） —— GET請(qǐng)求實(shí)現(xiàn)之任務(wù)進(jìn)度設(shè)置和通知監(jiān)聽（一）
4. AFNetworking源碼探究（四） —— GET請(qǐng)求實(shí)現(xiàn)之代理轉(zhuǎn)發(fā)思想（一）
5. AFNetworking源碼探究（五） —— AFURLSessionManager中NSURLSessionDelegate詳細(xì)解析（一）
6. AFNetworking源碼探究（六） —— AFURLSessionManager中NSURLSessionTaskDelegate詳細(xì)解析（一）
7. AFNetworking源碼探究（七） —— AFURLSessionManager中NSURLSessionDataDelegate詳細(xì)解析（一）
8. AFNetworking源碼探究（八） —— AFURLSessionManager中NSURLSessionDownloadDelegate詳細(xì)解析（一）
9. AFNetworking源碼探究（九） —— AFURLSessionManagerTaskDelegate中三個(gè)轉(zhuǎn)發(fā)代理方法詳細(xì)解析（一）
10. AFNetworking源碼探究（十） —— 數(shù)據(jù)解析之?dāng)?shù)據(jù)解析架構(gòu)的分析（一）
11. AFNetworking源碼探究（十一） —— 數(shù)據(jù)解析之子類中協(xié)議方法的實(shí)現(xiàn)（二）
12. AFNetworking源碼探究（十二） —— 數(shù)據(jù)解析之子類中協(xié)議方法的實(shí)現(xiàn)（三）
13. AFNetworking源碼探究（十三） —— AFSecurityPolicy與安全認(rèn)證 （一）
14. AFNetworking源碼探究（十四） —— AFSecurityPolicy與安全認(rèn)證 （二）
15. AFNetworking源碼探究（十五） —— 請(qǐng)求序列化之架構(gòu)分析（一）
16. AFNetworking源碼探究（十六） —— 請(qǐng)求序列化之協(xié)議方法的實(shí)現(xiàn)（二）
17. AFNetworking源碼探究（十七） —— _AFURLSessionTaskSwizzling實(shí)現(xiàn)方法交換（轉(zhuǎn)載）（一）
18. AFNetworking源碼探究（十八） —— UIKit相關(guān)之AFNetworkActivityIndicatorManager（一）
19. AFNetworking源碼探究（十九） —— UIKit相關(guān)之幾個(gè)分類（二）
20. AFNetworking源碼探究（二十） —— UIKit相關(guān)之AFImageDownloader圖像下載（三）
21. AFNetworking源碼探究（二十一） —— UIKit相關(guān)之UIImageView+AFNetworking分類（四）
回顧
上一篇講述了關(guān)于UIImageView的分類，用于下載圖像腊瑟。這一篇講述關(guān)于UIButton+AFNetworking的UIButton的一個(gè)分類聚假。其實(shí)看過上一篇的話块蚌，這一篇都是類似的，大家簡(jiǎn)單看一下就可以了膘格。
接口
我們先看一下API接口
#import <Foundation/Foundation.h>
#import <TargetConditionals.h>
#if TARGET_OS_IOS || TARGET_OS_TV
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@class AFImageDownloader;
/**
This category adds methods to the UIKit framework's `UIButton` class. The methods in this category provide support for loading remote images and background images asynchronously from a URL.
@warning Compound values for control `state` (such as `UIControlStateHighlighted | UIControlStateDisabled`) are unsupported.
*/
@interface UIButton (AFNetworking)
///------------------------------------
/// @name Accessing the Image Downloader
///------------------------------------
/**
Set the shared image downloader used to download images.
@param imageDownloader The shared image downloader used to download images.
*/
+ (void)setSharedImageDownloader:(AFImageDownloader *)imageDownloader;
/**
The shared image downloader used to download images.
*/
+ (AFImageDownloader *)sharedImageDownloader;
///--------------------
/// @name Setting Image
///--------------------
/**
Asynchronously downloads an image from the specified URL, and sets it as the image for the specified state once the request is finished. Any previous image request for the receiver will be cancelled.
If the image is cached locally, the image is set immediately, otherwise the specified placeholder image will be set immediately, and then the remote image will be set once the request is finished.
@param state The control state.
@param url The URL used for the image request.
*/
- (void)setImageForState:(UIControlState)state
withURL:(NSURL *)url;
/**
Asynchronously downloads an image from the specified URL, and sets it as the image for the specified state once the request is finished. Any previous image request for the receiver will be cancelled.
If the image is cached locally, the image is set immediately, otherwise the specified placeholder image will be set immediately, and then the remote image will be set once the request is finished.
@param state The control state.
@param url The URL used for the image request.
@param placeholderImage The image to be set initially, until the image request finishes. If `nil`, the button will not change its image until the image request finishes.
*/
- (void)setImageForState:(UIControlState)state
withURL:(NSURL *)url
placeholderImage:(nullable UIImage *)placeholderImage;
/**
Asynchronously downloads an image from the specified URL request, and sets it as the image for the specified state once the request is finished. Any previous image request for the receiver will be cancelled.
If the image is cached locally, the image is set immediately, otherwise the specified placeholder image will be set immediately, and then the remote image will be set once the request is finished.
If a success block is specified, it is the responsibility of the block to set the image of the button before returning. If no success block is specified, the default behavior of setting the image with `setImage:forState:` is applied.
@param state The control state.
@param urlRequest The URL request used for the image request.
@param placeholderImage The image to be set initially, until the image request finishes. If `nil`, the button will not change its image until the image request finishes.
@param success A block to be executed when the image data task finishes successfully. This block has no return value and takes three arguments: the request sent from the client, the response received from the server, and the image created from the response data of request. If the image was returned from cache, the response parameter will be `nil`.
@param failure A block object to be executed when the image data task finishes unsuccessfully, or that finishes successfully. This block has no return value and takes three arguments: the request sent from the client, the response received from the server, and the error object describing the network or parsing error that occurred.
*/
- (void)setImageForState:(UIControlState)state
withURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(nullable UIImage *)placeholderImage
success:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image))success
failure:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, NSError *error))failure;
///-------------------------------
/// @name Setting Background Image
///-------------------------------
/**
Asynchronously downloads an image from the specified URL, and sets it as the background image for the specified state once the request is finished. Any previous background image request for the receiver will be cancelled.
If the background image is cached locally, the background image is set immediately, otherwise the specified placeholder background image will be set immediately, and then the remote background image will be set once the request is finished.
@param state The control state.
@param url The URL used for the background image request.
*/
- (void)setBackgroundImageForState:(UIControlState)state
withURL:(NSURL *)url;
/**
Asynchronously downloads an image from the specified URL, and sets it as the background image for the specified state once the request is finished. Any previous image request for the receiver will be cancelled.
If the image is cached locally, the image is set immediately, otherwise the specified placeholder image will be set immediately, and then the remote image will be set once the request is finished.
@param state The control state.
@param url The URL used for the background image request.
@param placeholderImage The background image to be set initially, until the background image request finishes. If `nil`, the button will not change its background image until the background image request finishes.
*/
- (void)setBackgroundImageForState:(UIControlState)state
withURL:(NSURL *)url
placeholderImage:(nullable UIImage *)placeholderImage;
/**
Asynchronously downloads an image from the specified URL request, and sets it as the image for the specified state once the request is finished. Any previous image request for the receiver will be cancelled.
If the image is cached locally, the image is set immediately, otherwise the specified placeholder image will be set immediately, and then the remote image will be set once the request is finished.
If a success block is specified, it is the responsibility of the block to set the image of the button before returning. If no success block is specified, the default behavior of setting the image with `setBackgroundImage:forState:` is applied.
@param state The control state.
@param urlRequest The URL request used for the image request.
@param placeholderImage The background image to be set initially, until the background image request finishes. If `nil`, the button will not change its background image until the background image request finishes.
@param success A block to be executed when the image data task finishes successfully. This block has no return value and takes three arguments: the request sent from the client, the response received from the server, and the image created from the response data of request. If the image was returned from cache, the response parameter will be `nil`.
@param failure A block object to be executed when the image data task finishes unsuccessfully, or that finishes successfully. This block has no return value and takes three arguments: the request sent from the client, the response received from the server, and the error object describing the network or parsing error that occurred.
*/
- (void)setBackgroundImageForState:(UIControlState)state
withURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(nullable UIImage *)placeholderImage
success:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image))success
failure:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, NSError *error))failure;
///------------------------------
/// @name Canceling Image Loading
///------------------------------
/**
Cancels any executing image task for the specified control state of the receiver, if one exists.
@param state The control state.
*/
- (void)cancelImageDownloadTaskForState:(UIControlState)state;
/**
Cancels any executing background image task for the specified control state of the receiver, if one exists.
@param state The control state.
*/
- (void)cancelBackgroundImageDownloadTaskForState:(UIControlState)state;
@end
NS_ASSUME_NONNULL_END
#endif
其實(shí)這個(gè)接口主要包含四個(gè)模塊：
- 獲取圖像下載器
- 下載圖像
- 下載背景圖
- 取消下載圖像（包括圖像和背景圖）
獲取圖像下載器
下面我們就看一下獲取圖像下載器
/**
Set the shared image downloader used to download images.
@param imageDownloader The shared image downloader used to download images.
*/
+ (void)setSharedImageDownloader:(AFImageDownloader *)imageDownloader;
/**
The shared image downloader used to download images.
*/
+ (AFImageDownloader *)sharedImageDownloader;
圖像下載器是用runtime實(shí)現(xiàn)的峭范。
+ (AFImageDownloader *)sharedImageDownloader {
return objc_getAssociatedObject(self, @selector(sharedImageDownloader)) ?: [AFImageDownloader defaultInstance];
}
+ (void)setSharedImageDownloader:(AFImageDownloader *)imageDownloader {
objc_setAssociatedObject(self, @selector(sharedImageDownloader), imageDownloader, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
下載圖像
下面看一下下載圖像的實(shí)現(xiàn)。
- (void)setImageForState:(UIControlState)state
withURL:(NSURL *)url;
- (void)setImageForState:(UIControlState)state
withURL:(NSURL *)url
placeholderImage:(nullable UIImage *)placeholderImage;
- (void)setImageForState:(UIControlState)state
withURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(nullable UIImage *)placeholderImage
success:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image))success
failure:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, NSError *error))failure;
看一下實(shí)現(xiàn)
- (void)setImageForState:(UIControlState)state
withURL:(NSURL *)url
{
[self setImageForState:state withURL:url placeholderImage:nil];
}
- (void)setImageForState:(UIControlState)state
withURL:(NSURL *)url
placeholderImage:(UIImage *)placeholderImage
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request addValue:@"image/*" forHTTPHeaderField:@"Accept"];
[self setImageForState:state withURLRequest:request placeholderImage:placeholderImage success:nil failure:nil];
}
- (void)setImageForState:(UIControlState)state
withURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(nullable UIImage *)placeholderImage
success:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image))success
failure:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, NSError *error))failure
{
if ([self isActiveTaskURLEqualToURLRequest:urlRequest forState:state]) {
return;
}
[self cancelImageDownloadTaskForState:state];
AFImageDownloader *downloader = [[self class] sharedImageDownloader];
id <AFImageRequestCache> imageCache = downloader.imageCache;
//Use the image from the image cache if it exists
UIImage *cachedImage = [imageCache imageforRequest:urlRequest withAdditionalIdentifier:nil];
if (cachedImage) {
if (success) {
success(urlRequest, nil, cachedImage);
} else {
[self setImage:cachedImage forState:state];
}
[self af_setImageDownloadReceipt:nil forState:state];
} else {
if (placeholderImage) {
[self setImage:placeholderImage forState:state];
}
__weak __typeof(self)weakSelf = self;
NSUUID *downloadID = [NSUUID UUID];
AFImageDownloadReceipt *receipt;
receipt = [downloader
downloadImageForURLRequest:urlRequest
withReceiptID:downloadID
success:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, UIImage * _Nonnull responseObject) {
__strong __typeof(weakSelf)strongSelf = weakSelf;
if ([[strongSelf af_imageDownloadReceiptForState:state].receiptID isEqual:downloadID]) {
if (success) {
success(request, response, responseObject);
} else if(responseObject) {
[strongSelf setImage:responseObject forState:state];
}
[strongSelf af_setImageDownloadReceipt:nil forState:state];
}
}
failure:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, NSError * _Nonnull error) {
__strong __typeof(weakSelf)strongSelf = weakSelf;
if ([[strongSelf af_imageDownloadReceiptForState:state].receiptID isEqual:downloadID]) {
if (failure) {
failure(request, response, error);
}
[strongSelf af_setImageDownloadReceipt:nil forState:state];
}
}];
[self af_setImageDownloadReceipt:receipt forState:state];
}
}
這里和AFN中UIImageView以及SDWebImage中的調(diào)用形式都是一樣的瘪贱。這個(gè)和AFN中UIImageView的實(shí)現(xiàn)是類似的纱控，也不多說了。
主要就是首先判斷是否下載是否存在菜秦，如果存在甜害，那么就return，取消下載球昨。然后獲取下載器和緩存尔店，獲取緩存中的圖像，如果緩存圖像存在主慰，就進(jìn)行回調(diào)嚣州，如果緩存圖像不存在就開始進(jìn)行下載。
下載背景圖像
看一下調(diào)用接口
- (void)setBackgroundImageForState:(UIControlState)state
withURL:(NSURL *)url;
- (void)setBackgroundImageForState:(UIControlState)state
withURL:(NSURL *)url
placeholderImage:(nullable UIImage *)placeholderImage;
- (void)setBackgroundImageForState:(UIControlState)state
withURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(nullable UIImage *)placeholderImage
success:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image))success
failure:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, NSError *error))failure;
下面看一下實(shí)現(xiàn)
- (void)setBackgroundImageForState:(UIControlState)state
withURL:(NSURL *)url
{
[self setBackgroundImageForState:state withURL:url placeholderImage:nil];
}
- (void)setBackgroundImageForState:(UIControlState)state
withURL:(NSURL *)url
placeholderImage:(nullable UIImage *)placeholderImage
{
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request addValue:@"image/*" forHTTPHeaderField:@"Accept"];
[self setBackgroundImageForState:state withURLRequest:request placeholderImage:placeholderImage success:nil failure:nil];
}
- (void)setBackgroundImageForState:(UIControlState)state
withURLRequest:(NSURLRequest *)urlRequest
placeholderImage:(nullable UIImage *)placeholderImage
success:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, UIImage *image))success
failure:(nullable void (^)(NSURLRequest *request, NSHTTPURLResponse * _Nullable response, NSError *error))failure
{
if ([self isActiveBackgroundTaskURLEqualToURLRequest:urlRequest forState:state]) {
return;
}
[self cancelBackgroundImageDownloadTaskForState:state];
AFImageDownloader *downloader = [[self class] sharedImageDownloader];
id <AFImageRequestCache> imageCache = downloader.imageCache;
//Use the image from the image cache if it exists
UIImage *cachedImage = [imageCache imageforRequest:urlRequest withAdditionalIdentifier:nil];
if (cachedImage) {
if (success) {
success(urlRequest, nil, cachedImage);
} else {
[self setBackgroundImage:cachedImage forState:state];
}
[self af_setBackgroundImageDownloadReceipt:nil forState:state];
} else {
if (placeholderImage) {
[self setBackgroundImage:placeholderImage forState:state];
}
__weak __typeof(self)weakSelf = self;
NSUUID *downloadID = [NSUUID UUID];
AFImageDownloadReceipt *receipt;
receipt = [downloader
downloadImageForURLRequest:urlRequest
withReceiptID:downloadID
success:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, UIImage * _Nonnull responseObject) {
__strong __typeof(weakSelf)strongSelf = weakSelf;
if ([[strongSelf af_backgroundImageDownloadReceiptForState:state].receiptID isEqual:downloadID]) {
if (success) {
success(request, response, responseObject);
} else if(responseObject) {
[strongSelf setBackgroundImage:responseObject forState:state];
}
[strongSelf af_setBackgroundImageDownloadReceipt:nil forState:state];
}
}
failure:^(NSURLRequest * _Nonnull request, NSHTTPURLResponse * _Nullable response, NSError * _Nonnull error) {
__strong __typeof(weakSelf)strongSelf = weakSelf;
if ([[strongSelf af_backgroundImageDownloadReceiptForState:state].receiptID isEqual:downloadID]) {
if (failure) {
failure(request, response, error);
}
[strongSelf af_setBackgroundImageDownloadReceipt:nil forState:state];
}
}];
[self af_setBackgroundImageDownloadReceipt:receipt forState:state];
}
}
這個(gè)實(shí)現(xiàn)原理就不都說了河哑，和下載圖像中是類似的。
后記
本篇講述了UIButton+AFNetworking的UIButton的一個(gè)分類龟虎。分析了其下載器的下載璃谨、圖像的下載以及背景圖像的下載。
