使用 SwiftUI 时如何检查应用程序是否在 Apple Watch 上进入后台

Question

I know for an iOS app, you can use something like

Text("Hello, World!")
    .onReceive(NotificationCenter.default.publisher(for: UIApplication.willResignActiveNotification)) { _ in
        print("Moving to the background!")}

But I can not use willResignActiveNotification for WatchOS. What should I do to detect if my watchOS app enters the background?

Answer 1

You need to use the WKExtensionDelegate methods to monitor WatchKit app lifecycle events. There is no notification fired on these events, so you need to implement the applicationWillResignActive delegate method instead. You can publish a custom notification from there and make your View listen to those notifications or simply create a custom Publisher that emits a value on WKExtensionDelegate method calls.