iOS，檢查http或https服務器是否正在偵聽特定端口

Question

我需要查找Web服務器（有時在http中，有時在https中）是否正在偵聽。我希望同步進行，並有一個很短的超時時間，例如2-3秒。

什麼是正確的方法來做到這一點？我需要與iOS 5向後兼容。

更新：我需要在沒有外部庫的情況下執行此操作。

Answer 1

由於OP無法使用外部庫，實現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]); 
}