AFNetworking 2.0.0 后台下载

Posted 2023-02-24

技术标签:

【中文标题】AFNetworking 2.0.0 后台下载【英文标题】：AFNetworking 2.0.0 download in background 【发布时间】：2014-03-13 09:50:07 【问题描述】：

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下主页按钮时，它应该暂停（或在后台继续下载），如果我返回应用程序，它应该恢复。

我还需要显示下载进度。

我搜索了很多示例，但没有找到任何东西 'AFNetworking', '2.0.0'。

我为 ios 6.0+ 版本创建应用程序，所以我不能使用 AFHTTPSessionManager 或 AFURLSessionManager。

【问题讨论】：

也许你可以在这里找到解决方案：***.com/questions/12563753/… 【参考方案1】：

为了在 iOS 7 或更高版本的后台下载，我使用NSURLSession 和他们的NSURLSessionDownloadTask。

在 ProjectNavigator->YourProject->YourTarget->Capabilities (tab)->Background Modes 中打开 BackgroundMode

将NSURLSessin 的初始化器添加到您的 AppDelegate 方法 - (BOOL)application:(UIApplication* )application didFinishLaunchingWithOptions:(NSDictionary* )launchOptions 和下一个代码：

    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，不要忘记声明session 属性：

@property (nonatomic, strong) NSURLSession session;

还添加完成处理属性（如果您想在应用程序终止或崩溃后获取后台下载过程的回调，则需要它）：

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

在 AppDelegate 中添加委托方法：

-(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;

并声明您的类（在我的示例中的 AppDelegate.h 文件中）符合协议NSURLSessionDelegate，如下所示：

@interface AppDelegate : UIResponder <UIApplicationDelegate, NSURLSessionDelegate>

然后在某处添加下载任务：

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

因此，当您的应用程序在终止后启动时，您的会话将被恢复并且委托方法将被触发。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将被触发。

【讨论】：

【参考方案2】：

当您的应用程序进入后台暂停/停止下载操作时，当进入前台时恢复您在 NSOperation 队列中暂停的下载操作。阅读这几行代码可能会对您有所帮助：

        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，请使用：