iOS 如何dismiss所有modalViewController

从视图控制器A  presentViewController 到viewControllerB 再到c...等

获取A,A执行dismissViewController即可

//如果A已经present出了B已经presented出的话, A的presentedViewController是ViewControllerB，B的presentingViewController是ViewController

一个简单写法：

- (void)dissmissAllModalControllerAnimated:(BOOL)flag{

    UIViewController *presentingViewController =self.presentingViewController ;

   UIViewController *lastVC = self ;

   while (presentingViewController) {

       id temp = presentingViewController;

        presentingViewController = [presentingViewControllerpresentingViewController];

        lastVC = temp ;

    }

    [lastVC dismissViewControllerAnimated:flagcompletion:^{

        

    }];

}