ios - iOS，检查 http 或 https 服务器是否正在侦听特定端口

Question

我需要找出是否有网络服务器（有时在 http，有时在 https）正在监听。我更愿意同步进行，并有一个小的超时，例如 2-3 秒。

正确的方法是什么？我需要向后兼容 iOS 5。

更新：我需要在没有外部库的情况下做到这一点。

Answer 1

由于 OP 不能使用外部库，因此实现NSURLConnectionDelegate并使用：

- (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]);
}