ios - 使用实例变量来指示 View 是 Edit 还是 Show

Question

在 Start Developing iOS Apps (Swift): Implement Edit and Delete Behavior , 官方教程告诉我应该使用presentingViewController 和navigationController 来指示指定的 View 是Edit 还是Show，如下代码:

@IBAction func cancel(_ sender: UIBarButtonItem) {
    // Depending on style of presentation (modal or push presentation), this view controller needs to be dismissed in two different ways.
    let isPresentingInAddMealMode = presentingViewController is UINavigationController

    if isPresentingInAddMealMode {
        dismiss(animated: true, completion: nil)
    }
    else if let owningNavigationController = navigationController{
        owningNavigationController.popViewController(animated: true)
    }
    else {
        fatalError("The MealViewController is not inside a navigation controller.")
    }
}

添加 View 由modal呈现，编辑 View 由embed导航 Controller 呈现，但是我觉得这种方式不好理解和维护，不如引入一个 isEditOrShow View 中的实例变量来指示状态？如下所示:

@IBAction func cancel(_ sender: UIBarButtonItem) {
    // Depending on style of presentation (modal or push presentation), this view controller needs to be dismissed in two different ways.

    if isEditingOrShow = .edit{
        dismiss(animated: true, completion: nil)
    }
    else isEditingOrShow = .show{
        owningNavigationController.popViewController(animated: true)
    }
}

Answer 1

本教程解释说，有两种方法可以关闭 View Controller 。

例如，当您将 View Controller 呈现为模态时，您可以使用以下代码将其关闭。

dismiss(animated: true, completion: nil)

但是，如果您使用的是推送演示(导航 Controller )，那么您应该使用以下代码将其关闭。

owningNavigationController.popViewController(animated: true)

How about introduce a bool isEditOrShow instance varible in the view to indicate the state?

据我了解，您将不需要 isEditOrShow 变量。如果您有任何问题，请告诉我。