New error in iOS 5: WebKit discarded an uncaught exception

问题

I am trying to load a UIWebView with the Facebook OAuth authorization URL and I am using the following code. When my UIWebView loads with Facebook login page, I enter my credentials, then press the "Log in" button. When I hit the button I am getting the following error:

WebKit discarded an uncaught exception in the webView:decidePolicyForNavigationAction:request:frame:decisionListener:delegate: Application tried to present modally an active controller .

This same code works fine with iOS 4.3 and previous versions, but it doesn't work in iOS 5.0. I don't understand the problem, can anyone please help me?

NSString *redirectUrlString = @"http://www.facebook.com/connect/login_success.html";
NSString *authFormatString = @"https://graph.facebook.com/oauth/authorize?client_id=%@&redirect_uri=%@&scope=%@&type=user_agent&display=touch";

NSString *urlString = [NSString stringWithFormat:authFormatString, _apiKey, redirectUrlString, _requestedPermissions];
NSURL *url = [NSURL URLWithString:urlString];

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

NSURLRequest *request = [NSURLRequest requestWithURL:url];
[_webView loadRequest:request];

回答1:

Are you using the Ray Wenderlich code? (FBFunLoginDialog).. I found that this fixes it:

-(void)checkLoginRequired:(NSString *)urlString {
    NSLog(@"Url: %@",urlString);
    if ([urlString rangeOfString:@"login.php"].location != NSNotFound && [urlString rangeOfString:@"refid"].location == NSNotFound) {
            [_delegate displayRequired];
    } else if ([urlString rangeOfString:@"user_denied"].location != NSNotFound) {
         [_delegate closeTapped];
    }
}

回答2:

I have the same problem. I try to present view controller just after dismissing.

[self dismissModalViewControllerAnimated:YES];

When I try to do it without animation it works perfectly. use dismissViewControllerAnimated:completion:

来源：https://stackoverflow.com/questions/7812061/new-error-in-ios-5-webkit-discarded-an-uncaught-exception