Facebook login dialog will not work with UIAlertView, but does with UIButton

Question

I have this piece of code which I use for showing a login dialog/posting to the users wall:

_posting = YES;
// If we're not logged in, log in first...
if (![_session isConnected]) {
    self.loginDialog = nil;
    loginDialog = [[FBLoginDialog alloc] init]; 
    [_loginDialog show];
}
// If we have a session and a name, post to the wall!
else if (_facebookName != nil) {
    [self postToWall];
}
// Otherwise, we don't have a name yet, just wait for that to come through.

If I connect this code to a button, it works. However, when I place it inside the following method:

- (void)alertView:(UIAlertView *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
    // the user clicked one of the OK/Cancel buttons
    if (buttonIndex == 0)
    {
        NSLog(@"No");
    }
    else
    {       
        _posting = YES;
        // If we're not logged in, log in first...
        if (![_session isConnected]) {
            self.loginDialog = nil;
            _loginDialog = [[FBLoginDialog alloc] init];    
            [_loginDialog show];
        }
        // If we have a session and a name, post to the wall!
        else if (_facebookName != nil) {
            [self postToWall];
        }
        // Otherwise, we don't have a name yet, just wait for that to come through.

    }
}

It doesn't work..

Can anyone explain as to why this might be? When I say it doesn't work, I mean the dialog displays very briefly before closing itself. The app doesn't crash.

Answer 1

The waiting 1 sec is not a solution and doesn't actually fixes the problem.

The problem is that you listen to:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex

Which should be:

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex

Because at the clickedButtonAtIndex function the view isn't closed and this can cause problems.

Edit: To make it work in iOS 4 add your facebook login call to a method and call the following function in the didDismissWithButtonIndex:

[self performSelectorOnMainThread:@selector(facebookOpenAction) withObject:nil waitUntilDone:NO];

Answer 2

Figured it out, using the following line in the conditional instead of the facebook dialog code:

[self performSelector:@selector(showFBLoginDialog) withObject:nil afterDelay:1];

Seems you need to wait for the resources associated with the alert view to become available.

EDIT: The showFBLoginDialog method contains the dialog code that was originally in the conditional.

Answer 3

This is no longer an issue in iOS 5.

I don't see this as a solution, rather a quick fix/hack. Waiting for a 1 second delay may seem a little long, I wonder how low this delay can be set, the simulator shouldn't be used to asses this, and I no longer have a device running iOS 4. Would be interested to find out.

Maybe it would be better to add KVO to the alert view object to have a more precise idea of when it is destroyed, and trigger the dialog at that point.