ios - 如何在 iOS 中暂停/恢复/取消事件

Question

我有一个 UITabBarController，有时在 didSelectItem 委托(delegate)中我需要暂停事件并显示一个弹出窗口。如果用户确认事件继续，否则事件将被取消。这是我的代码:

class YC_TabBarController: UITabBarController {

    var prevIndex: Int!
    var exitAction: (()->Bool)?

    override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
        self.prevIndex = self.selectedIndex

        if self.prevIndex == 2 {

            guard self.exitAction != nil else {return}
            //pause
            let isExitAccepted: Bool = self.exitAction!()
            //if true -> resume
            //if false -> prevent from switching tab

        }

    }
}

我该怎么做？请帮忙

Answer 1

您应该在第一个 View Controller 中向 UITabBarControllerDelegate 确认，如果在 shouldSelect viewController 中选择了所需的 View Controller ，则返回 false。然后你应该显示你的弹出 View 。在弹出 View 确定/确认按钮中，您可以更改 self.tabBarController

的选定 View Controller

class ViewController: UIViewController,UITabBarControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.tabBarController?.delegate = self
    }

    func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
        if viewController is SecondViewController {
            //show alert
            return false
        } else {
            return true
        }
    }
    func popUpOkAction(_ sender:UIButton) {
        if let secVC = self.tabBarController?.viewControllers?.first(where: { $0 is SecondViewController }) {
            self.tabBarController?.selectedViewController = secVC
        }
    }
}

If you want to perform this from multiple view controllers rather than firstViewController you can confirm to UITabBarControllerDelegate in YC_TabBarController itself.