如何检查视图控制器是否添加到堆栈中 [英] How to check viewcontroller is added in stack or not

问题描述

我有两个视图控制器.我已通过按下按钮使用以下代码从一个视图导航到另一个视图.

I have two view controllers. I have navigated from one view to another view by press the button to using below code.

 *let secondViewController = self.storyboard!.instantiateViewControllerWithIdentifier("NotificationController") as! NotificationController

self.navigationController!.pushViewController(secondViewController, animated: true)*

对于背面，我使用下面的代码在条形按钮上使用条形按钮点击返回.

For the back, I am using bar button on bar button click for back using below code.

 self.navigationController?.popViewControllerAnimated(true)

所以我的问题是，如果我连续从一个视图转到另一个视图，那么它会添加到堆栈中.我只想在它已经添加到堆栈时显示另一个视图以停止添加它.它只添加一次.

So my problem is if I am going from one view to another view continuously then it added in a stack. I want to only show another view when it is already added to the stack to stop adding it.It only adds one time.

推荐答案

要检查导航堆栈是否包含特定类型的view controller，您可以使用:

To check whether the navigation stack contains a particular type of view controller, you can use:

if let viewControllers = self.navigationController?.viewControllers
{
    if viewControllers.contains(where: {
        return $0 is YourViewController
    })
    {
        //Write your code here
    }
}

要从导航堆栈中删除特定控制器，您需要对导航堆栈进行更改.

To remove a particular controller from navigation stack, you need to make changes to the navigation stack.

示例:

    if var viewControllers = self.navigationController?.viewControllers
    {
        for controller in viewControllers
        {
            if controller is UIViewController
            {
                viewControllers.removeElement(controller)
                self.navigationController?.viewControllers = viewControllers
            }
        }
    }

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