UIAlertView を UIAlertController で置き換えたら不具合が発生

{
   UIViewController *vc = [[[[UIApplication sharedApplication] delegate] window] rootViewController];

//  UIViewController *vc = [UIApplication sharedApplication].keyWindow.rootViewController

    UIAlertController *alert = [UIAlertController alertControllerWithTitle:strTitle message:strMessage preferredStyle: UIAlertControllerStyleAlert ];

    UIWindow *alertWin = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];

    [alert addAction:[UIAlertAction actionWithTitle:btnMessage style:UIAlertActionStyleDefault handler:^(UIAlertAction *action){

            [alertWin release];

    }]];

    if (windowId != nil) {
// どうしても表示できない場合

        alertWin.rootViewController = [[UIViewController alloc] init];

        alertWin.windowLevel = UIWindowLevelAlert + 1;

        [alertWin makeKeyAndVisible];

        [alertWin.rootViewController presentViewController:alert animated:NO completion:nil];

    } else

    {

        [vc presentViewController:alert animated:NO completion:nil];

    }
}