NSURLSessionDelegate connectionDidFinishLoading 方法没有被调用

Question

我正在使用NSURLSession 进行 JSON 解析。我正在编写这样的代码，但是当我运行应用程序时没有调用委托方法。即connectionDidFinishLoading 和didReceiveData 方法。如何调用NSURLSessionDelegate方法？

-(void)viewDidLoad {
    [super viewDidLoad];

    menuArr = [[NSMutableArray alloc]init];

    self.view.backgroundColor = [UIColor whiteColor];

    NSURL *url =[NSURL URLWithString:@"http://url"];

    dataTask = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data,NSURLResponse *response,NSError *error)
    {
        if(error == nil)
        {
            NSError *JSONError = nil;

            NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:data options:0 error:&JSONError];

            NSLog(@"Dictionary is:%@",dictionary);
        }
    }];

    [dataTask resume];
}

#pragma mark - NSURLSession delegate methods

- (BOOL)URLSession:(NSURLSession *)session dataTask:(NSURLSessionTask *)dataTask canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace*)protectionSpace
{
    BOOL isvalue = [protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust];

    return isvalue;
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition,NSURLCredential *credential))completionHandler
{
    [challenge.sender useCredential:[NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust] forAuthenticationChallenge:challenge];
    [challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)aresponse
{
    receivedData = [[NSMutableData alloc]init];
    [receivedData setLength:0];
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
{
    NSString * str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

    NSLog(@"Received String %@",str);
}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionTask *)dataTask connectionDidFinishLoading:(NSURLConnection *)conn
{
    NSError *error;

    NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:receivedData options:kNilOptions error:&error];

    NSString *str=[dict objectForKey:@"Status"];

    NSLog(@"Status Response is:%@",str);

    NSDictionary *jsonDict = [dict valueForKey:@"data"];

    NSLog(@"Json Dictionary is:%@",jsonDict);

    menuArr = [jsonDict valueForKey:@"Text"];

    NSLog(@"Item Name is:%@",menuArr);
}

Answer 1

• 添加这两个委托NSURLSessionDelegate, NSURLSessionDataDelegate

  -(void)viewDidLoad {
      [super viewDidLoad];
  
      [self sendHTTPPost];
  
  }
  -(void) sendHTTPPost
  {
      NSURLSessionConfiguration *defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
      NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration: defaultConfigObject delegate: self delegateQueue: [NSOperationQueue mainQueue]];
  
      NSURL * url = [NSURL URLWithString:@"http://api.geonames.org/citiesJSON?north=44.1&south=-9.9&east=-22.4&west=55.2&lang=de&username=demo"];
      NSMutableURLRequest * urlRequest = [NSMutableURLRequest requestWithURL:url];
  
      [urlRequest setHTTPMethod:@"POST"];
  
      NSURLSessionDataTask * dataTask = [defaultSession dataTaskWithRequest:urlRequest];
      [dataTask resume];
  
  }
  
  - (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
  didReceiveResponse:(NSURLResponse *)response
   completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler
  {
      NSLog(@"### handler 1");
  
      completionHandler(NSURLSessionResponseAllow);
  }
  
  - (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data
  {
      NSError *error;
  
      NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
  
      NSLog(@" dict=>> %@",dict);
  
  }
  - (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error
  {
      if(error == nil)
      {
          NSLog(@"Download is Succesfull");
      }
      else
          NSLog(@"Error %@",[error userInfo]);
  }
  

Answer 2

您正在使用共享会话。这是一个没有代表的预先存在的会话。如果您希望您的任务调用委托方法，您必须：

• 创建您自己的会话
• 在创建会话时指定要用作委托的对象
• 在该会话中创建任务，而不是在共享会话中。

Answer 3

您必须在类定义附近编写委托方法； 样品：
@interface MyControllerClass : UIViewController UIAlertViewDelegate in