ios - swift IOS : Call Specific function of UIviewController when open app from notification

Question

我想在点击通知打开应用程序时调用onDidReceiveNotification函数。 (ViewController 是第一个 View Controller ， Root View Controller )

当应用程序打开或在后台时，它工作正常，但是当应用程序未打开或在后台(不在内存中)并点击打开应用程序时，onDidReceiveNotification 函数不起作用打电话，

当使用点击推送通知打开应用程序时，我应该如何调用 onDidReceiveNotification 函数

ViewController.swift

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        NotificationCenter.default.removeObserver(self, name: .didReceiveAlert, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(ViewController.onDidReceiveNotification(_:)), name: .didReceiveAlert, object: nil)
    }

@objc func onDidReceiveNotification(_ notification:Notification) {
        print("Received Notification")
    }
}

AppDelegate.swift

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {            
    NotificationCenter.default.post(name: .didReceiveAlert, object: nil)       
}

Answer 1

当应用程序打开或在后台时调用NotificationCenter.defalut.post，当应用程序终止/关闭并使用通知打开时，获取实例并通过菜单调用onDidReceiveAlert 函数，请参见以下代码。

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {

    if application.applicationState == .background || application.applicationState == .active {
        NotificationCenter.default.post(name: .didReceiveAlert, object: nil)
    }else {
        let nav = window?.rootViewController as! UINavigationController
        let mainVC = nav.viewControllers.first as! ViewController
        mainVC.onDidReceiveAlert(nil)
    }
}

或者从 UINavigationController 堆栈中获取 ViewController 实例并直接调用 ViewController 的函数(不需要通知观察器)

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {

    let nav = window?.rootViewController as! UINavigationController
    let mainVC = nav.viewControllers.first as! ViewController
    mainVC.onDidReceiveAlert(nil)       
}

创建带有可选参数的函数，使用以下代码。

@objc func onDidReceiveAlert(_ notification:Notification? = nil) {
    print("Received Notification")
}