Set delegate:self.delegate in an alertView where self.delegate implements UIAlertViewDelegate protocol

Question

In my ViewController I have implemented the UIAlertViewDelegate and in my Model I have a method which creates an UIAlertView with the delegate set to self.delegate which is an instance of the ViewController. Then I try to call willPresentAlertView like this (in Model):

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Invalid operation"
            message:@"Cannot divide by 0!"
            delegate:self.delegate
            cancelButtonTitle:@"Cancel"
            otherButtonTitles:@"Undo division",nil];
[self.delegate willPresentAlertView:alert];

The willPresentAlertView is implemented in ViewController like this:

- (void)willPresentAlertView:(UIAlertView *)alertView
{
    [alertView show];
}

I then get an error Thread 1:EXC_BAD_ACCESS (code=2,adress=0xbf7fff6c) when calling [alert show].

If I set delegate to nil or self it works fine, but I want to call alertView:alertView clickedButtonAtIndex:buttonIndex when I press a button on the alert, which doesn't work with delegate set to nil or self. Only the ViewController implements these methods, why it should be self.delegate, or?

I want the model to invoke the alert, but I want the ViewController to handle the alert methods such as alertView:alertView clickedButtonAtIndex:buttonIndex.

How can this be done?

score 0 · Answer 1 · answered Jun 23 '14 at 15:23

it should be self [self willPresentAlertView:alert]

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Invalid operation"
            message:@"Cannot divide by 0!"
            delegate:self //self
            cancelButtonTitle:@"Cancel"
            otherButtonTitles:@"Undo division",nil];
[self willPresentAlertView:alert];//self again

Set delegate:self.delegate in an alertView where self.delegate implements UIAlertViewDelegate protocol

1 Answers1