iOS 11以下. 在模态进入的(presentViewController)控制器, 调用会出现退出当前控制器的问题.

估计原因: iOS 11 以后, DocumentViewController 是一个ViewController, dissmiss 并不会导致此类问题. 而在iOS10上, 当点击(空白区域或者 点击选择某个选项时)会出现此类Bug. 因为会调用iOS 方法里的 dismissViewControllerAnimated:completion.

我这边暂时解决方案是:
`
//override dismissViewControllerAnimated: completion

• (void)dismissViewControllerAnimated:(BOOL)flag completion:(void (^)(void))completion {

    UIViewController *topVC = [[self topViewController]; //获取栈顶控制器
  
    if ([topVC isKindOfClass:[WebVC class]]) {
  
        if (self.isClickExit) { //WebVC 上点击dissmiss 按钮
            [super dismissViewControllerAnimated:flag completion:completion];
        }
    } else {
        [[self topViewController] dismissViewControllerAnimated:flag completion:completion];
    }
  

}
`

Start by reproducing the modal-controller flow on iOS 10, focusing on taps on the blank area or an option that trigger dismissViewControllerAnimated:. Trace the presentViewController and dismissViewControllerAnimated: path around DocumentViewController, WebVC, and the top view controller. Done means those interactions no longer dismiss the current controller unexpectedly while an explicit WebVC exit still works.