NSURLSession download and nsurlsession background download

NSURLSession download and nsurlsession background download

Ios7 introduces NSURLSession, which supports new network operations related to the background:

1. Background upload and download;
2. network operations can be paused and restored without using nsoperation and nsurlsession APIs.
3. As a configurable container: for example, you can set some attributes of the http header and save them in the session without repeated configuration.
4. sub-classes are supported and private sessions are supported.
5. Improved the authentication callback. Previously, the nsurlconnection authentication callback could not match the request. The callback may come from any request. Now, each request can be performed in the specified proxy method.

Next we will briefly study how to download:

:

Main Code:

1. Define several global variables

@interface ViewController (){    NSURLSessionDownloadTask * _task;    NSData * _data;    NSURLSession * _session;    NSURLRequest * _request;    UIProgressView * _pro;    UIImageView * _imageView;    }

2. Add an image progress bar to the view

_imageView=[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 300, 300)];    _imageView.center=self.view.center;    [self.view addSubview:_imageView];    _pro=[[UIProgressView alloc] initWithFrame:CGRectMake(_imageView.frame.origin.x, _imageView.frame.origin.y+400, 300, 40)];

3. Add buttons to the view (add three buttons in the same way)

UIButton * button = [[UIButton alloc] initWithFrame: CGRectMake (50, _ imageView. frame. origin. y + 400 + 20, 50, 40)]; button. backgroundColor = [UIColor blueColor]; [button setTitle: @ "" forState: UIControlStateNormal]; [button addTarget: self action: @ selector (ddLoad) forControlEvents: UIControlEventTouchUpInside]; button. layer. borderWidth = 1; button. layer. borderColor = [UIColor blueColor]. CGColor; button. layer. cornerRadius = 5; [self. view addSubview: button];

4. Network status monitoring through AFNetworkReachabilityManager

-(Void) _ checkNet {// enable network status monitoring [[AFNetworkReachabilityManager sharedManager] startMonitoring]; [AFNetworkReachabilityManager sharedManager] running: ^ (AFNetworkReachabilityStatus status) {if (status = AFNetworkReachabilityStatusReachableViaWiFi) {NSLog (@ "current is wifi");} if (status = success) {NSLog (@ "current is 3G ");} if (status = AFNetworkReachabilityStatusNotReachable) {NSLog (@ "No network currently");} if (status = AFNetworkReachabilityStatusUnknown) {NSLog (@ "currently unknown network") ;}}] ;}

5. Start download

-(Void) ddLoad {NSURLSessionConfiguration * config = [NSURLSessionConfiguration defaultSessionConfiguration]; _ session = [NSURLSession sessionWithConfiguration: config delegate: self delegateQueue: nil]; // NSURL * url = [NSURL URLWithString: @ src]; _ request = [NSURLRequest requestWithURL: url]; _ task = [_ session downloadTaskWithRequest: _ request]; NSLog (@ "Start loading"); [_ task resume];}

6. Set pause and reply.

-(Void) pause {// pause NSLog (@ "pause download"); [_ task cancelByProducingResumeData: ^ (NSData * resumeData) {_ data = resumeData;}]; _ task = nil;}-(void) resume {// restore NSLog (@ "resume download"); if (! _ Data) {NSURL * url = [NSURL URLWithString: @ src]; _ request = [NSURLRequest requestWithURL: url]; _ task = [_ session downloadTaskWithRequest: _ request];} else {_ task = [_ session downloadTaskWithResumeData: _ data];} [_ task resume];}

7. The agent method is used to save the downloaded file and monitor the download progress.

# Pragma mark-delegate-(void) URLSession :( NSURLSession *) session downloadTask :( NSURLSessionDownloadTask *) downloadTask failed :( NSURL *) location {NSURL * url = [NSURL fileURLWithPath: @ "/Users/jredu/Desktop/tt.png"]; NSFileManager * manager = [NSFileManager defaultManager]; [manager moveItemAtURL: location toURL: url error: nil]; dispatch_async (dispatch_get_main_queue (), ^ {NSData * data = [manager contentsAtPath: @ "/Users/jredu/Desktop/tt.png"]; UIImage * image = [UIImage alloc] initWithData: data]; _ imageView. image = image; UIAlertView * alert = [[UIAlertView alloc] initWithTitle: nil message: @ "download completed" delegate: self cancelButtonTitle: @ "OK" otherButtonTitles: nil]; [alert show];});}-(void) URLSession :( NSURLSession *) session downloadTask :( bytes *) downloadTask didWriteData :( int64_t) bytesWritten minutes :( int64_t) interval :( int64_t) totalBytesExpectedToWrite {CGFloat progress = (totalBytesWritten * 1.0)/totalBytesExpectedToWrite; dispatch_async (dispatch_get_main_queue (), ^ {_ pro. progress = progress ;});}

 

Author: Jerry Education
Source: http://www.cnblogs.com/jerehedu/
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