iOS，检查http或https服务器是否正在侦听特定端口

Question

我需要查找一个Web服务器（有时是http，有时是https）正在侦听。我宁愿同步这样做并且有一个小的超时，例如2-3秒。

这样做的正确方法是什么？我需要向后兼容iOS 5。

更新：我需要在没有外部库的情况下完成。

Answer 1

由于OP无法使用外部库，请实施 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]);
}