Question

我有结构：

* - TabBarViewController（Root）

* - NavigationViewController

* ---- ChatViewController

* - NavigationViewController

* ---- MenuViewController

当我切换tabbar项目时，（Chat，Menu）中的viewWillAppear只调用一次，但每次切换时都会调用NavigationVC。

切换项目时是否可以在聊天和菜单ViewControllers中自动调用viewWillAppeare？

super.viewWillAppear是内部方法。

我的代码如下：

class TabBarController: UITabBarController {

override func viewDidLoad() {
    super.viewDidLoad()
    let v1 = storyboard!.instantiateViewController(withIdentifier: "ChatViewController")
    let v2 = storyboard!.instantiateViewController(withIdentifier: "MenuViewController")
    viewControllers = [v1,v2]

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

class ChatViewController: UIViewController {
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print(self,#function)
    }
}

class MenuViewController: UIViewController {
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print(self,#function)
    }
}

它适用于清晰的新项目，但是在旧的（我工作的地方，我有功能的掠夺，不起作用）

StoryboardId链接到Storyboard

中的NavigationViewController

Answer 1

您的问题不明确是将viewcontroller添加到tabbarcontroller和导航控制器。我在故事板中创建了所有内容。 View将出现在视图控制器中：

 override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print("Menu View will appear")
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        print("Chat View will appear")
    }

切换时能够低于输出：

Menu View will appear
Chat View will appear
Menu View will appear
Chat View will appear

Answer 2

我发现了问题：在extension UINavigationController我有方法

    open override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        if !UserDefaults.standard.isUserPresented {
            navigationBar.barTintColor = .rgbColor(red: 43, green: 43, blue: 43, alpha: 1)
        } else {
            navigationBar.barTintColor = .rgbColor(red: 100, green: 100, blue: 100, alpha: 1)
        }
    }

这个块viewWillAppear在NavigationBar中的子视图控制器中

ViewWillAppear未在tabbar项目视图控制器中调用

2 个答案: