AssociatedObjectExample.m

- (void)askUserAQuestion{
    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle : @"Question Time"
                          message : @"What do you want to do ?"
                          delegate : self
                          cancelButtonTitle : @"Cancel"
                          otherButtonTitle : @"Continue",
                          nil];
  [alert show];
}
// UIAlertViewDelegate protocol method
- (void)alertView(UIAlertView *)alertView
        clickedButtonIndex: (NSInteger)buttonIndex{
        if (buttonIndex == 0){
          [self doCancel];
        }else{
          [self doContinue];
        }
}

/* what is the problem here the problem is what if we have more than one alert do we have to 
write each condition and make code copy-paste
thats wrong in this case we can make an associated object like below
*/

static void  *myAlertViewKey = @"myAlertViewKey";
- (void)askUserAQuestion{
    UIAlertView *alert = [[UIAlertView alloc]
                          initWithTitle : @"Question Time"
                          message : @"What do you want to do ?"
                          delegate : self
                          cancelButtonTitle : @"Cancel"
                          otherButtonTitle : @"Continue",
                          nil];
  void (^block)(NSInteger) = ^(NSInteger buttonIndex){
        if (buttonIndex == 0){
          [self doCancel];
        }else{
          [self doContinue];
        }
  }
   objc_setAssociatedObject(alert,myAlertViewKey,block,OBJC_ASSOCIATION_COPY);
  [alert show];
}

// UIAlertViewDelegate protocol method with associated object method
- (void)alertView(UIAlertView *)alertView
        clickedButtonIndex: (NSInteger)buttonIndex{
      void (^block)(NSInteger) = objc_getAssociatedObject(alertView,myAlertViewKey);
      block(buttonIndex);
}