導(dǎo)語
現(xiàn)在NSURLConnection在開發(fā)中會使用的越來越少展氓，iOS9已經(jīng)將NSURLConnection廢棄沙兰，現(xiàn)在最低版本一般適配iOS7北秽，所以也可以使用锄蹂。

NSURLConnection相對于NSURLSession,安全性低畴蹭。NSURLConnection下載有峰值坦仍，比較麻煩處理。
盡管適配最低版本iOS7叨襟，也可以使用NSURLSession繁扎。AFN已經(jīng)不支持NSURLConnection。
NSURLSession：默認(rèn)是掛起狀態(tài)糊闽，如果要請求網(wǎng)絡(luò)梳玫，需要開啟。

 [NSURLSession sharedSession] 獲取全局的NSURLSession對象右犹。在iPhone的所有app共用一個全局session.     NSURLSessionUploadTask -> NSURLSessionDataTask -> NSURLSessionTask     NSURLSessionDownloadTask -> NSURLSessionTask     NSURLSessionDownloadTask下載提澎，默認(rèn)下載到tmp文件夾。下載完成后刪除臨時文件念链。所以我們要在刪除文件之前盼忌，將它移動到Cache里。

NSURLSession詳解
NSURLSession基礎(chǔ)

NSURLSession代理
NSURLSession大文件下載
NSURLSession斷點(diǎn)續(xù)傳

1.NSURLSession基礎(chǔ)
第一種網(wǎng)絡(luò)請求方法

//創(chuàng)建URL
NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php?username=haha&password=123"];
//創(chuàng)建請求
// NSURLRequest * request = [NSURLRequest requestWithURL:url];
//創(chuàng)建Session
NSURLSession * session = [NSURLSession sharedSession];
//創(chuàng)建任務(wù)
NSURLSessionDataTask * task = [session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
}];
//開啟網(wǎng)絡(luò)任務(wù)
[task resume];

第二種網(wǎng)絡(luò)請求方法
//創(chuàng)建URL
NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php?username=haha&password=123"];
//創(chuàng)建請求
NSURLRequest * request = [NSURLRequest requestWithURL:url];
//創(chuàng)建Session
NSURLSession * session = [NSURLSession sharedSession];
//創(chuàng)建任務(wù)
NSURLSessionDataTask * task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);

}];
//開啟網(wǎng)絡(luò)任務(wù)
[task resume];

POST請求

NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php"];

NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:url];

//設(shè)置請求方法
request.HTTPMethod = @"POST";

//設(shè)置請求體
request.HTTPBody = [@"username=haha&password=123" dataUsingEncoding:NSUTF8StringEncoding];

[[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    
    NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
    
}] resume];

下載文件
NSURL * url = [NSURL URLWithString:[@"http://192.168.1.200/DOM解析.mp4" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];

NSURLSession * session = [NSURLSession sharedSession];

NSURLSessionDownloadTask * downloadTask = [session downloadTaskWithURL:url completionHandler:^(NSURL * _Nullable location, NSURLResponse * _Nullable response, NSError * _Nullable error) {
    
    //location 下載到沙盒的地址
    NSLog(@"下載完成%@",location);

    //response.suggestedFilename 響應(yīng)信息中的資源文件名
    NSString * cachesPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:response.suggestedFilename];
    
    NSLog(@"緩存地址%@",cachesPath);
    
    //獲取文件管理器
    NSFileManager * mgr = [NSFileManager defaultManager];
    //將臨時文件移動到緩存目錄下
    //[NSURL fileURLWithPath:cachesPath] 將本地路徑轉(zhuǎn)化為URL類型
    //URL如果地址不正確掂墓，生成的url對象為空
    
    [mgr moveItemAtURL:location toURL:[NSURL fileURLWithPath:cachesPath] error:NULL];
    
}];

[downloadTask resume];

2.NSURLSession代理

• (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

//  全局session
//    NSURLSession * session = [NSURLSession sharedSession];
//創(chuàng)建自定義session
//NSURLSessionConfiguration 的 配置
//[[NSOperationQueue alloc] init] 也可以寫成 nil

NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php?username=haha&password=123"];

NSURLSession * session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];

NSURLSessionDataTask * task = [session dataTaskWithURL:url];

[task resume];

}

//接收到服務(wù)器響應(yīng)

• (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
  didReceiveResponse:(NSURLResponse *)response
  completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {

  NSLog(@"%s",FUNCTION);

  //允許接受服務(wù)器回傳數(shù)據(jù)
  completionHandler(NSURLSessionResponseAllow);
  }

//接收服務(wù)器回傳的數(shù)據(jù),有可能執(zhí)行多次

• (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
  didReceiveData:(NSData *)data {

  NSLog(@"%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
  }

//請求成功或失敗

• (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {

  NSLog(@"%@",error);
  }

3.NSURLSession大文件下載

import "ViewController.h"

@interface ViewController ()<NSURLSessionDownloadDelegate>

@end

@implementation ViewController

• (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.

  NSLog(@"%@",NSSearchPathForDirectoriesInDomains(9, 1, 1));
  }

• (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {

  NSURLSession * session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];

  NSURLSessionDownloadTask * task = [session downloadTaskWithURL:[NSURL URLWithString:[@"http://192.168.1.200/DOM解析.mp4"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];

  [task resume];

}

/*

監(jiān)測臨時文件下載的數(shù)據(jù)大小谦纱，當(dāng)每次寫入臨時文件時，就會調(diào)用一次

bytesWritten 單次寫入多少
totalBytesWritten 已經(jīng)寫入了多少
totalBytesExpectedToWrite 文件總大小

*/

• (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
  didWriteData:(int64_t)bytesWritten
  totalBytesWritten:(int64_t)totalBytesWritten
  totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {

  //打印下載百分比
  NSLog(@"%f",totalBytesWritten * 1.0 / totalBytesExpectedToWrite);

}

//下載完成

• (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
  didFinishDownloadingToURL:(NSURL *)location {

NSString * cachesPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:downloadTask.response.suggestedFilename];

NSFileManager * mgr = [NSFileManager defaultManager];

[mgr moveItemAtURL:location toURL:[NSURL fileURLWithPath:cachesPath] error:NULL];

}

• (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {

  NSLog(@"%@",error);
  }

4.NSURLSession斷點(diǎn)續(xù)傳

import "ViewController.h"

@interface ViewController ()<NSURLSessionDownloadDelegate>

@property (nonatomic, strong) NSURLSessionDownloadTask * task;

@property (nonatomic, strong) NSData * resumeData;

@property (nonatomic, strong) NSURLSession * session;

@end

@implementation ViewController

//故事板中開始按鈕的響應(yīng)方法

• (IBAction)start:(id)sender {

  NSURLSession * session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[[NSOperationQueue alloc] init]];

  self.session = session;

  self.task = [session downloadTaskWithURL:[NSURL URLWithString:[@"http://192.168.1.68/丁香花.mp3"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]];

  [self.task resume];
  }

//故事板中暫停按鈕的響應(yīng)方法

• (IBAction)pause:(id)sender {

  //暫停就是將任務(wù)掛起

  [self.task cancelByProducingResumeData:^(NSData *resumeData) {
  //保存已下載的數(shù)據(jù)

    self.resumeData = resumeData;
  

  }];
  }
  //繼續(xù)按鈕的響應(yīng)方法

• (IBAction)resume:(id)sender {

  //可以使用ResumeData創(chuàng)建任務(wù)

  self.task = [self.session downloadTaskWithResumeData:self.resumeData];

  //開啟繼續(xù)下載
  [self.task resume];

}

• (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.

  NSLog(@"%@",NSSearchPathForDirectoriesInDomains(9, 1, 1));
  }

/*

監(jiān)測臨時文件下載的數(shù)據(jù)大小梆暮，當(dāng)每次寫入臨時文件時服协，就會調(diào)用一次

bytesWritten 單次寫入多少
totalBytesWritten 已經(jīng)寫入了多少
totalBytesExpectedToWrite 文件總大小

*/

• (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
  didWriteData:(int64_t)bytesWritten
  totalBytesWritten:(int64_t)totalBytesWritten
  totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {

  //打印下載百分比
  NSLog(@"%f",totalBytesWritten * 1.0 / totalBytesExpectedToWrite);

}

//下載完成

• (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
  didFinishDownloadingToURL:(NSURL *)location {

NSString * cachesPath = [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:downloadTask.response.suggestedFilename];

NSFileManager * mgr = [NSFileManager defaultManager];

[mgr moveItemAtURL:location toURL:[NSURL fileURLWithPath:cachesPath] error:NULL];

}

• (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {

  NSLog(@"%@",error);
  }