Question

I have created category for UIAlertView and overridden the delegate method willPresentAlertView but my method in the category not getting fired.

sample code :

@interface UIAlertView (CustomAlert)
@end

@implementation UIAlertView (CustomAlert)
- (void)willPresentAlertView:(UIAlertView *)alertView1
{

    for (UIView *sub in [alertView1 subviews])
    {
        if([sub class] == [UIImageView class])
        {
            ((UIImageView *)sub).image=nil;
            ((UIImageView *)sub).backgroundColor = [UIColor blackColor];
        }
    }

    [alertView1.layer setBorderColor:[[UIColor whiteColor] CGColor]];
    [alertView1.layer setCornerRadius:0];
    [alertView1.layer setBorderWidth:2];
}

@end

Answer 1

If your intent is providing a default implementation for willPresentAlertView delegate method, then your approach (defining willPresentAlertView in a UIAlertView category) is correct. You only need to pass the alert itself as a delegate so that the method is called:

 UIAlertView* alert = ...
 alert.delegate = alert;

If you do not do that, your delegate method will not be called.

On the other hand, I doubt that defining a default implementation like that is really of great use, since in principle each alert would need its own specific delegate method.