使用AFNetworking下载中心

Question

我正在开发一个应用程序，用户可以下载书籍，当用户开始下载他仍然在屏幕（模态屏幕），直到下载完成，但如果它是一本大书？这将是一个问题所以我希望用户关闭屏幕，但监视SlidingMenu或ViewController的下载进度，如果他们是多个文件也可以监视他们的进度，我使用此代码在同一屏幕下载文件。

NSString *pathURL=item.path;
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:pathURL]];
    operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [[paths objectAtIndex:0] stringByAppendingPathComponent:item.fileName];
operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];

[operation setDownloadProgressBlock:^(NSUInteger bytesRead, NSInteger totalBytesRead, NSInteger totalBytesExpectedToRead) {
    mbProcess.progress=(float)totalBytesRead / totalBytesExpectedToRead;
        _loadinglabel.text=[[NSString alloc]initWithFormat:@"Downloading %d %",(int)(100*((float)totalBytesRead/totalBytesExpectedToRead))];
    _progressDialogdet.progress=(float)totalBytesRead/totalBytesExpectedToRead;
    }];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"Successfully downloaded file to %@", path);

} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
         //   [mbProcess removeFromSuperview];


}];
    [operation start];