ios - 如何从 viewController 到 appdelegate 进行通信？

Question

我想与我的 appdelegate 通信，换句话说，我想从多个 View 向 AppDelegate 发送数据，这可能吗？

我找到了这段代码

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

这个问题: Bi-Directional communication between ViewController and AppDelegate with swift 2 for iOS

有可能使用 NSNotification 进行通信吗？

Answer 1

是的，Notification 可以完成您想要做的事情。在 View Controller 中，发布通知:

class YourViewController: UIViewController {

    ...

    @IBAction func buttonPressed(_ sender: Any) {
        NotificationCenter.default.post(name: "ViewControllerButtonPressed", object: nil)
    }
}

然后，在您的 AppDelegate 中，添加一个 Notification 观察者来观察此通知名称的帖子:

class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        ...

        //Add the observer
        //This observer will call the "doSomething" function every time NotificationCenter.default.post(name: "ViewControllerButtonPressed", object: nil) is called
        NotificationCenter.default.addObserver(self, selector: #selector(doSomething), name: "ViewControllerButtonPressed", object: nil)
    }

    @objc func doSomething() {
        print("A button was pressed in one of your view controllers!")
    }

}

附加建议: 为了使事情更简单，您可以扩展 Notification.Name 来为名称创建静态 String 值:

public extension Notification.Name {
    static let ButtonPressed = Notification.Name("ViewControllerButtonPressed")
}

这可以取代

NotificationCenter.default.post(name: "ViewControllerButtonPressed", object: nil)

与

NotificationCenter.default.post(name: NSNotification.Name.ButtonPressed, object: nil)

和

NotificationCenter.default.addObserver(self, selector: #selector(doSomething), name: "ViewControllerButtonPressed", object: nil)

与

NotificationCenter.default.addObserver(self, selector: #selector(doSomething), name: NSNotification.Name.ButtonPressed, object: nil)

实现上述方法是可选的，但可以防止在使用 Notification 时出现拼写错误。