present一个视图时，隐藏底部的tabbar.有何办法让tabbar重新显示出来？

UIViewController *presentedVC = [[UIViewController alloc]init];

presentedVC.modalPresentationStyle = UIModalPresentationOverCurrentContext;

AppDelegate *appdelegate=(AppDelegate*)[[UIApplication sharedApplication] delegate];

appdelegate.window.rootViewController.definesPresentationContext = YES;

[appdelegate.window.rootViewController presentViewController:presentedVC  animated:YES completion:nil];