Iphone facebook graph api教程获取错误

我正在使用这些教程在iphone中实现facebook graph api 但当我点击facebook登录按钮时，我在nslog文件上出现了如下错误

2013-01-09 18:50:54.509 FBFun[3279:11303] *** WebKit discarded an uncaught exception in the webView:decidePolicyForNavigationAction:request:frame:decisionListener: delegate: <NSInvalidArgumentException> Application tried to present modally an active controller <ViewController: 0x75446a0>.

但是我没有成功，任何人都有关于这篇文章的答案，请与我分享

离开该教程：

https://developers.facebook.com/ios/

使用这一款，对您来说很简单，并且分步骤进行：

从这里下载Facebook新SDK，您不需要像ray教程前面那样单独调用：

https://developers.facebook.com/ios/

最简单的教程供初学者使用和访问facebook SDK中的Graph API/FQL等：

https://developers.facebook.com/docs/tutorials/ios-sdk-tutorial/

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希望能有所帮助。

嘿，我在代码中遇到了同样的问题，使用 但经过数小时的研究和一些代码调试后，问题解决了

我为了方便而更改的代码

• （BOOL）webView:（UIWebView*）webView应加载WithRequest:（NSURLRequest*）请求导航类型：（UIWebViewNavigationType）导航类型{
  NSString*urlString=request.URL.absoluteString
  [self-checkForAccessToken:urlString]
  if（self.isViewLoaded&&self.view.window）{
  }
  [self-CheckLogin Required:urlString]
  返回TRUE

}

-（void）checkLoginRequired:（NSString*）urlString{

    NSLog(@"Url: %@",urlString);

    if ([urlString rangeOfString:@"login.php"].location != NSNotFound && [urlString rangeOfString:@"refid"].location == NSNotFound) {
        NSLog(@"Login Required");
        [_delegate displayRequired];

    } else if ([urlString rangeOfString:@"login_success"].location != NSNotFound) {
        NSLog(@"login_success");

       //any thing you want to do after log in success.
    }

    NSLog(@"Url: %@",urlString);

    if ([urlString rangeOfString:@"login.php"].location != NSNotFound && [urlString rangeOfString:@"refid"].location == NSNotFound) {
        NSLog(@"Login Required");
        [_delegate displayRequired];

    } else if ([urlString rangeOfString:@"login_success"].location != NSNotFound) {
        NSLog(@"login_success");

       //any thing you want to do after log in success.
    }