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];
         }
     }