pop&dismiss

//dismiss到根视图
- (void)dismissToRootViewController{
    UIViewController *vc = self;
    while (vc.presentingViewController) {
        vc = vc.presentingViewController;
    }
    [vc dismissViewControllerAnimated:YES completion:nil];
}
//这种更有效

　　UIViewController *vc =self.presentingViewController;

    while (![vc isKindOfClass:[[UIApplication sharedApplication].keyWindow.rootViewController class]]) {

        vc = vc.presentingViewController;

    }

    [vc dismissViewControllerAnimated:YES completion:nil];

    //dismiss到指定界面
    UIViewController *vc =self.presentingViewController;
    while (![vc isKindOfClass:[[UIApplication sharedApplication].keyWindow.rootViewController class]]) {
        vc = vc.presentingViewController;
    }
    [vc dismissViewControllerAnimated:YES completion:nil];

  [self.navigationController popToRootViewControllerAnimated:YES];//pop到根视图

  for (UIViewController *controller in self.navigationController.viewControllers) {
        if ([controller isKindOfClass:[WekeWordLockViewController class]]) {
            WekeWordLockViewController *vc = (WekeWordLockViewController *)controller;
            [self.navigationController popToViewController:vc animated:YES];
        }
    }