AFNetworking 2.0.0在后台下载

Question

我正在使用'AFNetworking', '2.0.0'下载数据。

我需要下载大文件。当用户锁定屏幕或按Home键时，应该暂停（或继续在后台下载），如果我返回到应用程序，它应该恢复。

此外我需要显示下载的进度。

我搜索了很多例子，但是没有找到任何东西'AFNetworking', '2.0.0'。

我为iOS 6.0+版本创建应用程序，因此我无法使用AFHTTPSessionManager或AFURLSessionManager。

Answer 1

也许你使用DTDownload会更好： https://github.com/Cocoanetics/DTDownload

据我所知，它并没有什么报告进度。

编辑：有一个很好的教程超过在AppCoda，关于使用NSURLSessionTask： http://www.appcoda.com/background-transfer-service-ios7/

Answer 2

当你的应用程序切换到后台暂停/停止下载操作，并配备在前台时恢复中的NSOperation队列已暂停下载操作。 阅读这些代码可以帮助你：

 AFDownloadRequestOperation *operation = [[AFDownloadRequestOperation alloc] initWithRequest:request targetPath:filePath shouldResume:YES]; 




     [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) { 
      //handel completion 
      [operations removeObjectForKey:audioItem.filename]; 

     }failure:^(AFHTTPRequestOperation *operation, NSError *error) { 
      //handel failure 
        operation = [operations objectForKey:audioItem.filename]; 
        [operation cancel]; 
        [operations removeObjectForKey:audioItem.filename]; 
        if (error.code != NSURLErrorCancelled) { 
         [self showErrorAlert]; 
         NSLog(@"Error: %@", error); 
        } 




     }]; 


    [operation setProgressiveDownloadProgressBlock:^(NSInteger bytesRead, long long totalBytesRead, long long totalBytesExpected, long long totalBytesReadForFile, long long totalBytesExpectedToReadForFile) { 
      //handel progress 
      NSNumber *progress = [NSNumber numberWithFloat:((float)totalBytesReadForFile/(float)totalBytesExpectedToReadForFile)]; 
      float progress=progress.floatValue; 
      [self performSelectorOnMainThread:@selector(updateProgressBar:) withObject:[NSArray arrayWithObjects:audioItem, progress, nil] waitUntilDone: YES]; 

     }]; 

     [operation setShouldExecuteAsBackgroundTaskWithExpirationHandler:^{ 
      // TODO: Clean up operations 
      NSLog(@"App has been in background too long, need to clean up any connections!"); 
     }]; 

     [operations setValue:operation forKey:@"key"]; // store the NSOperation for further use in application to track its status. 
     [downloadQueue addOperation:operation];//here downloadQueue is NSOperationQueue instance that manages NSOperations. 

要暂停下载操作使用本：

[operation pause]; 

要继续使用该行的类别：

[operation resume]; 

Answer 3

对于后台下载在iOS 7或更高版本上，我使用NSURLSession和NSURLSessionDownloadTask。在ProjectNavigator-> YourProject-> YourTarget->功能上BackgroundMode

开关（标签） - >背景模式

加入您的AppDelegate方法- (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions为NSURLSessin与下一个代码的初始化剂：

NSURLSessionConfiguration *sessionConfiguration; 
    NSString *someUniqieIdentifierForSession = @"com.etbook.background.DownloadManager"; 
    if ([[[[[UIDevice currentDevice] systemVersion] componentsSeparatedByString:@"."] firstObject] integerValue] >= 8) { 
//This code for iOS 8 and greater 
     sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:someUniqieIdentifierForSession]; 
    } else { 
this code for iOS 7 
     sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfiguration:someUniqieIdentifierForSession]; 
    } 
    sessionConfiguration.HTTPMaximumConnectionsPerHost = 5; 
    self.session = [NSURLSession sessionWithConfiguration:sessionConfiguration 
               delegate:self 
              delegateQueue:[NSOperationQueue mainQueue]]; 

当然，不要忘了申报session属性搭配：

@property (nonatomic, strong) NSURLSession session; 

另外补充完成处理特性（它会需要，如果你想申请终止或崩溃后获得后台下载程序的回调）：

@property (nonatomic, copy) void(^backgroundTransferCompletionHandler)(); 

添加委托方法中的AppDelegate：

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

    NSError *error; 
    NSFileManager *fileManager = [NSFileManager defaultManager]; 

    NSString *destinationFilename = downloadTask.originalRequest.URL.lastPathComponent; 
    NSURL *destinationURL = [[[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject] URLByAppendingPathComponent:destinationFilename]; 

    if ([fileManager fileExistsAtPath:[destinationURL path]]) { 
     [fileManager removeItemAtURL:destinationURL error:nil]; 
    } 
    [fileManager copyItemAtURL:location 
         toURL:destinationURL 
         error:&error]; 
} 

-(void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{ 
    if (error != nil) { 
     NSLog(@"Download completed with error: %@", [error localizedDescription]); 
    } 
    else{ 
     NSLog(@"Download finished successfully."); 
} 

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

    if (totalBytesExpectedToWrite == NSURLSessionTransferSizeUnknown) { 
     NSLog(@"Unknown transfer size"); 
    } 
    else{ 
     NSLog(@"progress = %lld Mb of %lld Mb", totalBytesWritten/1024/1024, totalBytesExpectedToWrite/1024/1024); 
    } 
} 

-(void)URLSessionDidFinishEventsForBackgroundURLSession:(NSURLSession *)session{ 
    ETBAppDelegate *appDelegate = [UIApplication sharedApplication].delegate; 

    // Check if all download tasks have been finished. 
    [self.session getTasksWithCompletionHandler:^(NSArray *dataTasks, NSArray *uploadTasks, NSArray *downloadTasks) { 

     if ([downloadTasks count] == 0) { 
      if (appDelegate.backgroundTransferCompletionHandler != nil) { 
       // Copy locally the completion handler. 
       void(^completionHandler)() = appDelegate.backgroundTransferCompletionHandler; 

       // Make nil the backgroundTransferCompletionHandler. 
       appDelegate.backgroundTransferCompletionHandler = nil; 

       [[NSOperationQueue mainQueue] addOperationWithBlock:^{ 
        // Call the completion handler to tell the system that there are no other background transfers. 
        completionHandler(); 

        // Show a local notification when all downloads are over. 
        UILocalNotification *localNotification = [[UILocalNotification alloc] init]; 
        localNotification.alertBody = @"All files have been downloaded!"; 
        [[UIApplication sharedApplication] presentLocalNotificationNow:localNotification]; 
       }]; 
      } 
     } 
    }]; 
} 


//Background download support (THIS IMPORTANT METHOD APPLICABLE ONLY IN YOUR AppDelegate.m FILE!!!) 
-(void)application:(UIApplication *)application handleEventsForBackgroundURLSession:(NSString *)identifier completionHandler:(void (^)())completionHandler{ 
    self.backgroundTransferCompletionHandler = completionHandler; 
} 

并声明你的类（在AppDelegate中。在我的例子.h文件）符合协议NSURLSessionDelegate喜欢这里：

NSURLSessionDownloadTask *task = [self.session downloadTaskWithURL:[NSURL URLWithString:urlString]]; 
task.taskDescription = [NSString stringWithFormat:@"Downloading file %@", [urlString lastPathComponent]]; 
[task resume]; 

所以，当你的应用程序结束后开始，您的会话将被恢复并委托方法：

@interface AppDelegate : UIResponder <UIApplicationDelegate, NSURLSessionDelegate> 

然后再添加下载任务将被解雇。此外，如果您的应用程序将从后台唤醒到前台，您的应用程序委托方法也会被触发。