Question

我正在向我的服务器进行NSURLConnection但responseData在connectionDidFinishLoading中最终为空，我无法弄清楚原因。这是连接的代码：

NSMutableData *responseData;

- (void)myFunction:(id)sender {

  NSString *url = @"http://www.example.com/";

  NSURL *URL = [NSURL URLWithString:url];

  NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0];

  NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];

  [connection start];
}


// NSURLConnection Delegates
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
  [responseData setLength:0];
}


- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
  [responseData appendData:data];
}


- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

} // end connectionDidFinishLoading

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
  NSLog(@"Connection error: %@",[error description]);
}

Answer 1

responseData未初始化：）

Answer 2

典型！就在我完成发布问题时，答案就在我面前。我从未初始化responseData。所以在viewDidLoad我添加了以下一行：

- (void)viewDidLoad
{

  [super viewDidLoad];

  responseData = [NSMutableData data];

}

为什么我的NSURLConnection返回null？

2 个答案: