Question

我创建了＆＃34; updateheading＆＃34;在设置包中

如果用户离开应用程序，请转到设置更改值，当用户返回应用程序时，locationManager应根据更新的值开始/停止。

但该应用程序未运行viewWillAppear。如何阅读更新值？

private let locationManager : CLLocationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()

    locationManager.requestWhenInUseAuthorization()
    locationManager.delegate = self
}
override func viewWillAppear(_ animated: Bool) {

    let userDefault = UserDefaults.standard
    let updateheading = userDefault.object(forKey: "updateheading") as! Bool
    if(updateheading){
        locationManager.startUpdatingHeading()
    }else{
        locationManager.stopUpdatingHeading()
    }
}

Answer 1

视图控制器不响应应用程序状态。它是AppDelegate的责任。但您可以订阅通知。

var observer: Any?

override func viewWillAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    observer = NotificationCenter.default.addObserver(forName: NSNotification.Name.UIApplicationDidBecomeActive, object: nil, queue: .main) { (_) in
        doUpdate()
    }
    doUpdate()
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    observber = nil
}

doUpdate是您当前的代码。

PS：＆＃34;如果覆盖viewWillAppear，则必须在实施中的某个时刻调用super。＆＃34; （c）Apple Docs

我回到App时如何阅读设置包？

1 个答案: