NSURLSession詳解

導語

• 現在NSURLConnection在開發中會使用的越來越少，iOS9已經將NSURLConnection廢棄，現在最低版本一般適配iOS7，所以也可以使用。

• NSURLConnection相對於NSURLSession,安全性低。NSURLConnection下載有峰值，比較麻煩處理。
• 盡管適配最低版本iOS7，也可以使用NSURLSession。AFN已經不支持NSURLConnection。
•  NSURLSession：默認是掛起狀態，如果要請求網絡，需要開啟。

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

NSURLSession詳解

1. NSURLSession基礎

2. NSURLSession代理
3. NSURLSession大文件下載
4. NSURLSession斷點續傳

1.NSURLSession基礎

• 第一種網絡請求方法  

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

• 第二種網絡請求方法

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

• POST請求

NSURL * url = [NSURL URLWithString:@"http://192.168.1.200/login.php"];
    
    NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:url];
    
    //設置請求方法
    request.HTTPMethod = @"POST";
    
    //設置請求體
    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] 將本地路徑轉化為URL類型
        //URL如果地址不正確，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];
    
}

//接收到服務器響應

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
didReceiveResponse:(NSURLResponse *)response
 completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {
    
    NSLog(@"%s",__FUNCTION__);
    
    //允許接受服務器回傳數據
    completionHandler(NSURLSessionResponseAllow);
}

//接收服務器回傳的數據,有可能執行多次
- (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];

}

/* 
 
 監測臨時文件下載的數據大小，當每次寫入臨時文件時，就會調用一次
 
 bytesWritten 單次寫入多少
 totalBytesWritten  已經寫入了多少
 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斷點續傳

 

#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方法
- (IBAction)pause:(id)sender {
    
    //暫停就是將任務掛起
    
    [self.task cancelByProducingResumeData:^(NSData *resumeData) {
        //保存已下載的數據

        self.resumeData = resumeData;
    }];
}
//繼續按鈕的響應方法
- (IBAction)resume:(id)sender {
    
    //可以使用ResumeData創建任務
    
    self.task = [self.session downloadTaskWithResumeData:self.resumeData];
    
    //開啟繼續下載
    [self.task resume];
    
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    NSLog(@"%@",NSSearchPathForDirectoriesInDomains(9, 1, 1));
}


/* 
 
 監測臨時文件下載的數據大小，當每次寫入臨時文件時，就會調用一次
 
 bytesWritten 單次寫入多少
 totalBytesWritten  已經寫入了多少
 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);
}