如何在 WatchOS 的基于页面的界面中显示警报？

Question

我的手表应用程序有一个基于页面的界面，我真的不知道当前屏幕上的 InterfaceController 是什么（可能是 4 个中的 1 个），但是无论应用程序在哪个屏幕上，我都需要弹出警报。鉴于我不一定知道哪个 InterfaceController 是“当前的”，我如何显示警报？下面的代码只有在用户导航到这个 InterfaceController 时才会运行。如果用户不在该页面上，那么我会在控制台中看到此错误2019-09-22 15:42:01.597663-0400 Watch Extension[501:526217] Warning: Attempt to present <PUICAlertSheetController: 0x18158c00> on <SPInterfaceViewController: 0x1795e800> whose view is not in the window hierarchy!

extension WorkoutControlsInterfaceController: WorkoutEndedDelegate {
    func timerEndedCheckToSeeIfWorkoutEnded(_ manager: WorkoutManager) {
        let endWorkoutAction = WKAlertAction(title: "End Workout", style: .default, handler: {
            print("User has selected to end the workout")
            self.workoutManager?.stopWorkout()

        })
        let cancelAction = WKAlertAction(title: "Cancel", style: .cancel, handler: {

        })
        self.becomeCurrentPage()
        self.presentAlert(withTitle: "Workout Ended?", message: "It looks like your workout may have ended?", preferredStyle: .alert, actions: [endWorkoutAction, cancelAction])
    }


}

Answer 1

您可以使用共享WKExtesion 对象中的visibileInterfaceController 属性；

extension WorkoutControlsInterfaceController: WorkoutEndedDelegate {
    func timerEndedCheckToSeeIfWorkoutEnded(_ manager: WorkoutManager) {
        let endWorkoutAction = WKAlertAction(title: "End Workout", style: .default, handler: {
            print("User has selected to end the workout")
            self.workoutManager?.stopWorkout()

        })
        let cancelAction = WKAlertAction(title: "Cancel", style: .cancel, handler: {

        })

        WKExtension.shared().visibleInterfaceController?.presentAlert(withTitle: "Workout Ended?", message: "It looks like your workout may have ended?", preferredStyle: .alert, actions: [endWorkoutAction, cancelAction])
    }


}