How to write event handlers for buttons in UIAlertView?

Question

Say I have a alert view like follows in obj c

UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"title" message:@"szMsg" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:@"download"];         [alert show];         [alert release]; 

Now we have 2 buttons on the alert view (Ok & Download), how to write an event handler for the Download one?

Answer 1

First you will need to add the UIAlertViewDelegate to your header file like below:

Header file (.h)

@interface YourViewController : UIViewController<UIAlertViewDelegate>  

Implementation File (.m)

UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"title" message:@"szMsg" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:@"download"];         [alert show];         [alert release];  - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {     if (buttonIndex == 0)     {         //Code for OK button     }     if (buttonIndex == 1)     {         //Code for download button     } } 

Answer 2

Now that most iOS devices have firmare versions with blocks support it’s an anachronism to use the clumsy callback API to handle button presses. Blocks are the way to go, see for example the Lambda Alert classes on GitHub:

CCAlertView *alert = [[CCAlertView alloc]     initWithTitle:@"Test Alert"     message:@"See if the thing works."]; [alert addButtonWithTitle:@"Foo" block:^{ NSLog(@"Foo"); }]; [alert addButtonWithTitle:@"Bar" block:^{ NSLog(@"Bar"); }]; [alert addButtonWithTitle:@"Cancel" block:NULL]; [alert show];