NSURLSession学习笔记（二）Session Task

/* 使用NSURLSessionDownloadTask下载文件 */  

- (IBAction)downloadFile:(id)sender {  

    [self.spinner startAnimating];  

      

    NSURL *URL = [NSURL URLWithString:@"/image/w%3D2048/sign=6be5fc5f718da9774e2f812b8469f919/"];  

    NSURLRequest *request = [NSURLRequest requestWithURL:URL];  

    NSURLSession *session = [NSURLSession sharedSession];  

    NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithRequest:request  

                                                            completionHandler:  

                                              ^(NSURL *location, NSURLResponse *response, NSError *error) {  

                                                  [self showResponseCode:response];  

                                                    

                                                  // 输出下载文件原来的存放目录  

                                                  NSLog(@"%@", location);  

                                                    

                                                  // 设置文件的存放目标路径  

                                                  NSString *documentsPath = [self getDocumentsPath];  

                                                  NSURL *documentsDirectoryURL = [NSURL fileURLWithPath:documentsPath];  

                                                  NSURL *fileURL = [documentsDirectoryURL URLByAppendingPathComponent:[[response URL] lastPathComponent]];  

                                                    

                                                  // 如果该路径下文件已经存在，就要先将其移除，在移动文件  

                                                  NSFileManager *fileManager = [NSFileManager defaultManager];  

                                                  if ([fileManager fileExistsAtPath:[fileURL path] isDirectory:NULL]) {  

                                                      [fileManager removeItemAtURL:fileURL error:NULL];  

                                                  }  

                                                  [fileManager moveItemAtURL:location toURL:fileURL error:NULL];  

                                                    

                                                  // 在webView中加载图片文件  

                                                  NSURLRequest *showImage_request = [NSURLRequest requestWithURL:fileURL];  

                                                  [self.webView loadRequest:showImage_request];  

                                                    

                                                  [self.spinner stopAnimating];  

                                              }];  

      

    [downloadTask resume];  

}  

  

/* 获取Documents文件夹的路径 */  

- (NSString *)getDocumentsPath {  

    NSArray *documents = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);  

    NSString *documentsPath = documents[0];  

    return documentsPath;  

}