iOS，检查http或https服务器是否正在侦听特定端口

Question

我需要查找Web服务器（有时在http中，有时在https中）是否正在侦听。我希望同步进行，并有一个很短的超时时间，例如2-3秒。

什么是正确的方法来做到这一点？我需要与iOS 5向后兼容。

更新：我需要在没有外部库的情况下执行此操作。

Answer 1

由于OP无法使用外部库，实现NSURLConnectionDelegate及用途：

- (void)testUrl:(NSString *)url 
{ 
    // Create the request. 
    NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:url] 
               cachePolicy:NSURLRequestReloadIgnoringCacheData 
              timeoutInterval:3.0]; 

    NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
{ 
    NSHTTPURLResponse* httpResponse = (NSHTTPURLResponse*)response; 
    int responseStatusCode = [httpResponse statusCode]; 

    NSLog(@"GOT STATUS CODE: %d", responseStatusCode); 
} 

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{ 
    NSLog(@"Done!"); 
} 

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{ 
    NSLog(@"Connection failed! Error - %@ %@", 
      [error localizedDescription], 
      [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]); 
}