UIAlertView is deprecated on iOS 8. Therefore, to create an alert on iOS 8 and above, it is recommended to use UIAlertController:
UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Title" message:@"Alert Message" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *defaultAction = [UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action){
// Enter code here
}];
[alert addAction:defaultAction];
// Present action where needed
[self presentViewController:alert animated:YES completion:nil];
This is how I have implemented it.