Télécharger plusieurs fichiers en utilisant NSURLSession

Question

Je veux télécharger plusieurs fichiers à partir d'un tableau d'URL à partir du serveur un par un.

J'ai besoin de montrer la progression de chaque fichier de téléchargement, où l'utilisateur peut également l'annuler.

ViewControllerh:

#import <UIKit/UIKit.h> 

@interface ViewController : UIViewController { 
    IBOutlet UIView *vw_download; 
    IBOutlet UILabel *lbl_BookTitle; 
    IBOutlet UILabel *lbl_BookDes; 
    IBOutlet UILabel *lbl_downloadStatus; 
    IBOutlet UIImageView *img_todownload; 
    IBOutlet UIProgressView *vw_downloadbar; 
    IBOutlet UIButton *btn_stopDownload; 
} 

-(IBAction)btn_stopDownloading:(id)sender; 

@end 

ViewController.m:

#import "ViewController.h" 

@interface ViewController()<NSURLSessionDelegate> { 
    NSMutableArray *downloadLinksArray; 
    NSURLSession *session ; 
    NSURLSessionDownloadTask *task; 
} 
@end 

@implementation ViewController 

- (void)viewDidLoad { 
    downloadLinksArray=[[NSMutableArray alloc]initWithObjects:@"URL1",@"URL2", @"URL3", @"URL4", nil]; 

    [vw_downloadbar setProgress:0]; 
    lbl_downloadStatus.text=[NSString stringWithFormat:@"Downloading in Progress"]; 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view, typically from a nib. 
} 

-(IBAction)startDownload:(id)sender { 
    //[self startChapterDownLoad]; 

    for (int i=0;i< [downloadLinksArray count];i++) { 
     NSURL *Url= [NSURL URLWithString:[NSString stringWithFormat:@"%@",[downloadLinksArray objectAtIndex:i]]]; 

     NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration]; 

     session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:[NSOperationQueue mainQueue]]; 

     NSURLRequest* request = [NSURLRequest requestWithURL:Url]; 

     task = [session downloadTaskWithRequest:request]; 

     [task resume]; 
    } 
} 

-(void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite { 
    CGFloat percentDone = (double)totalBytesWritten/(double)totalBytesExpectedToWrite; 
    // Notify user. 

    [self performSelectorOnMainThread:@selector(updateProgress:) withObject:[NSNumber numberWithFloat:percentDone] waitUntilDone:NO]; 
} 

- (void) updateProgress:(NSNumber *)percent { 
    [vw_downloadbar setProgress:percent.floatValue]; 
} 

-(void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location { 
    // Either move the data from the location to a permanent location, or do something with the data at that location. 
} 

-(IBAction)btn_stopDownloading:(id)sender { 
    [task cancel]; 
    [vw_downloadbar setProgress:0]; 
} 

Answer 1

si u voulez télécharger plusieurs fichiers et quand il termine u souhaitez notifier:

s'il vous plaît vérifiez le code - en utilisant NSFileManager:

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration]; 
NSURLSession    *session  = [NSURLSession sessionWithConfiguration:configuration]; 

NSString  *documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0]; 
NSFileManager *fileManager = [NSFileManager defaultManager]; 

for (NSString *filename in self.filenames) 
{ 
    NSURL *url = [baseURL URLByAppendingPathComponent:filename]; 
    NSURLSessionTask *downloadTask = [session downloadTaskWithURL:url completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) { 

     NSString *finalPath = [documentsPath stringByAppendingPathComponent:filename]; 

     BOOL success; 
     NSError *fileManagerError; 
     if ([fileManager fileExistsAtPath:finalPath]) { 
      success = [fileManager removeItemAtPath:finalPath error:&fileManagerError]; 
      NSAssert(success, @"removeItemAtPath error: %@", fileManagerError); 
     } 

     success = [fileManager moveItemAtURL:location toURL:[NSURL fileURLWithPath:finalPath] error:&fileManagerError]; 
     NSAssert(success, @"moveItemAtURL error: %@", fileManagerError); 

     NSLog(@"finished %@", filename); 
    }]; 
    [downloadTask resume]; 
} 

u peut aller avec: NSOperationQueue

NSOperationQueue *queue = [[NSOperationQueue alloc] init]; 
queue.maxConcurrentOperationCount = 4; 

NSBlockOperation *completionOperation = [NSBlockOperation blockOperationWithBlock:^{ 
    [[NSOperationQueue mainQueue] addOperationWithBlock:^{ 
     [self methodToCallOnCompletion]; 
    }]; 
}]; 

for (NSURL* url in urlArray) 
{ 
    NSBlockOperation *operation = [NSBlockOperation blockOperationWithBlock:^{ 
     NSData *data = [NSData dataWithContentsOfURL:url]; 
     NSString *filename = [documentsPath stringByAppendingString:[url lastPathComponent]]; 
     [data writeToFile:filename atomically:YES]; 
    }]; 
    [completionOperation addDependency:operation]; 
} 

[queue addOperations:completionOperation.dependencies waitUntilFinished:NO]; 
[queue addOperation:completionOperation]; 

il sera montre le pourcentage de téléchargement de votre fichier:

u peut changer selon ur exigence: (je l'ai fait pas testé cela mais ça va marcher).

@property (nonatomic, retain) NSMutableData *dataToDownload; 
@property (nonatomic) float downloadSize; 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration]; 

    NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate: self delegateQueue: [NSOperationQueue mainQueue]]; 

    NSURL *url = [NSURL URLWithString: @"your url"]; 
    NSURLSessionDataTask *dataTask = [defaultSession dataTaskWithURL: url]; 

    [dataTask resume]; 
} 

- (void)didReceiveMemoryWarning { 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

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

    progressBar.progress=0.0f; 
    _downloadSize=[response expectedContentLength]; 
    _dataToDownload=[[NSMutableData alloc]init]; 
} 

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data { 
    [_dataToDownload appendData:data]; 
    progressBar.progress=[ _dataToDownload length ]/_downloadSize; 
}