Close UIAlertView and Replace with Another

I'm running an application that requires LocationServices be enabled. I'm checking if they are by making a call to the service and c开发者_JAVA百科atching the error. In the error case, I want to pop up an alertview notifying the user to activate location services. I have another AlertView open already when this test happens. I want to close that one and give the user the dialog box I mentioned previously.

Currently, I have

case kCLErrorDenied: // CL access has been denied (eg, user declined location use)

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"NOTICE" 
               message:@"Sorry, this application needs your location.  Please select 'Allow' when asked to use your current location.  You don't need to be on or near the trail."
                 delegate:self
              cancelButtonTitle:nil 
              otherButtonTitles:@"EXIT"];
   [alert show];
   [alert release];
   //exit(0);
   break;

This causes the app to just exit. I had an NSLog output in there so I know it gets to this case.

here you are specifying delegate:self, then it searches for alert handlers declared at UIAlertViewDelegate and when it doesn't find it crashes.

So you should define

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex

in your class.

Also you can implement other methods of UIAlertViewDelegate which will help you in your required task.

You need to keep track of the previous alert with an instance variable, and call the method to dismiss that previous dialog before showing the new one. You also need a delegate handler for the alert.