iOS 8.3 UIAlertController crashes when trying to add a textfield

Question

I have an iPad app. I am creating an UIAlertController and adding a textfield. It crashes. It only crashes when I add a textfield.

let alert = UIAlertContr         


        

Answer 1

There does seem to a bug in iOS 8.3 related alerts. It manifests on both (deprecated) UIAlertView and the iOS8-only UIAlertController. When I attempt to add a textfield to either of these controllers, I get the following crash:

 *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'The layout constraints still need update after sending -updateConstraints to <_UIKeyboardLayoutAlignmentView: 0x792d28e0; frame = (0 0; 0 0); userInteractionEnabled = NO; layer = >.
_UIKeyboardLayoutAlignmentView or one of its superclasses may have overridden -updateConstraints without calling super. Or, something may have dirtied layout constraints in the middle of updating them.  Both are programming errors.'

Alerts without textfields are OK, but showing a UIAlertView with style UIAlertViewStylePlainTextInput or showing a UIAlertController with a textfield added via addTextFieldWithConfigurationHandler will result in the above crash.

The fix seems to be to set a prophylactic frame on the UIAlertController before calling show. This frame is overridden before show, but prevents the crash.

if (NSClassFromString(@"UIAlertController")) {
    // iOS8
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Alert"
                                                                   message:@"Be alert, not alarmed"
                                                            preferredStyle:UIAlertControllerStyleAlert];
    [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
        textField.keyboardType = UIKeyboardTypeEmailAddress;

    }];
    alert.view.frame = CGRectMake(0.0, 0.0, 320.0, 400.0); // Workaround iOS8.3 bug - set this to larger than you'll need

    [self presentViewController:alert animated:YES completion:^{
        [alert.textFields[0] becomeFirstResponder];
    }];
} else {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert"
                                                    message:@"Be alert, not alarmed"
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
    alert.alertViewStyle = UIAlertViewStylePlainTextInput;
    UITextField *emailField = [alert textFieldAtIndex:0];
    emailField.keyboardType = UIKeyboardTypeEmailAddress;

    [alert show];
}