UIAlertView button action? Xcode

I have a UIALertView that shows with this code that asks you to rate the application in the appstore.

UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Rate on the Appstore!"message:@""delegate:self cancelButtonTitle:@"Later"otherButtonTitles:@"OK",nil];
    [alert show];
 

But i cannot figure out how to add a action to the OK button that takes you to the app in the appstore.

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