这是正确的。

if ([CLLocationManager locationServicesEnabled]){

    NSLog(@"Location Services Enabled");

    if ([CLLocationManager authorizationStatus]==kCLAuthorizationStatusDenied){
        alert = [[UIAlertView alloc] initWithTitle:@"App Permission Denied"     
                                           message:@"To re-enable, please go to Settings and turn on Location Service for this app." 
                                          delegate:nil 
                                 cancelButtonTitle:@"OK" 
                                 otherButtonTitles:nil];
        [alert show];
    }
}