ios - 文件下载器使用 NSURLSessionTask downloadTask

Question

我想创建文件下载管理器来下载多个具有下载百分比和播放暂停删除功能的文件。

我尝试使用以下代码成功下载多个文件...但无法添加进度条请帮忙

for (int i = 0; i < [arr_bookChapter count]; i++) {
  NSURLSessionTask * downloadTask = [session downloadTaskWithURL: downloadfileUrl completionHandler: ^ (NSURL * location, NSURLResponse * response, NSError * error) {
      if (error == nil) {
          NSHTTPURLResponse * httpResponse = (NSHTTPURLResponse * ) response;

          if ([httpResponse statusCode] == 200) {

              //download file save here                                                      

              dispatch_queue_t backgroundQueue = dispatch_queue_create("dispatch_queue_#1", 0);
              dispatch_async(backgroundQueue, ^ {

                  dispatch_async(dispatch_get_main_queue(), ^ {
                      // NSError *error;

                      //download complete here

                  });
              });
          }
      } else {
          //faile                                                  
      }

  }];
  [downloadTask resume];
}

在这里我得到了swift code :有人可以为 Objective-C 创建或提供解决方案

Answer 1

你可以很容易地做到这一点，你只需要在你的 ViewContorller 中实现这些委托(delegate)。

<NSURLSessionDataDelegate, NSURLSessionDelegate, NSURLSessionTaskDelegate>

然后您需要遵循以下代码:

@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;
}