Question

I have code setting up a UIAlertView:

-(IBAction)showMessage
{
//NSInteger *buttonIndex = NULL;
UIAlertView *message = [[UIAlertView alloc] initWithTitle:nil 
message:nil 
delegate:nil 
cancelButtonTitle:@"Cancel" 
otherButtonTitles:@"Email",@"SMS",@"Facebook",@"Twitter", nil];
[message show];
}

and code explaining what to do once the user makes a choice:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 1){
        [self openMail];
    }
    else if (buttonIndex == 2)
//etc.
}

But what I can’t figure out is how to connect the two. The obvious answer is to add a line to the first piece of code calling alertView: clickedButtonAtIndex on UIAlertView *message, but how do you assign buttonIndex? How do you tell alertView whether the user has chosen Facebook, Email, etc?

Answer 1

Add to the header file if you haven’t already:

@interface YourClass : UIViewController <UIAlertViewDelegate>
{
}

…etc

and in your AlertView code change delegate:nil to delegate:self

For more information have a look at the Apple Docs:
http://developer.apple.com/library/ios/#DOCUMENTATION/UIKit/Reference/UIAlertViewDelegate_Protocol/UIAlertViewDelegate/UIAlertViewDelegate.html

From the docs:
The button indices start at 0. If this is the cancel button index, the alert view is canceling. If -1, the cancel button index is not set.