Ios BatteryMonitoringEnabled属性状态是否未变为true

我正在尝试制作一个简单的电池电量打印应用程序，但无法将

isBatteryMonitoringEnabled

属性状态设置为

true

。我做了每一件事，但我没有做到

以下是我迄今为止所做的工作：

import UIKit

class ViewController: UIViewController {

    @IBAction func Start(_ sender: Any) {
        UIDevice.current.isBatteryMonitoringEnabled = true

        var batteryLevel: Float {
            return UIDevice.current.batteryLevel
        }

        print(batteryLevel)       
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

每当我在模拟器上编译并运行这段代码时，我总是得到-1.0作为输出（这意味着状态是未知的）

---

如果有人帮我解决问题，我将不胜感激

在实际设备上运行时，以下内容对我有效。在应用程序委托中，我启用电池监控：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    UIDevice.current.isBatteryMonitoringEnabled = true
    return true
}

我有一个View Controller，可以在其中手动检查设备是否正在充电，或者在设备插入或拔出时接收通知

类ViewController:UIViewController{ @IBOutlet弱var chargingLabel:UILabel

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(batteryStateChanged(_:)), name: UIDevice.batteryStateDidChangeNotification, object: nil)
    updateBatteryUI()
}

@objc func batteryStateChanged(_ notification:Notification) {
    if UIDevice.current.batteryState == .charging {
        UIApplication.shared.isIdleTimerDisabled = true
        chargingLabel.text = "Charging"
    } else {
        chargingLabel.text = "Not Charging"
    }
}

func updateBatteryUI() {
    if UIDevice.current.batteryState == .charging {
        UIApplication.shared.isIdleTimerDisabled = true
        chargingLabel.text = "Charging"
    } else {
        chargingLabel.text = "Not Charging"
    }
}

---

}

模拟器没有电池。在真实设备上运行。即使在真实设备上运行，我也会遇到同样的问题。你找到解决办法了吗？