Xpre 11•Swift 5.1
首先只需启用电池监控：
UIDevice.current.isBatteryMonitoringEnabled = true
然后，您可以创建一个计算属性以返回电池电量：
电池电量从0.0（完全放电）到1.0（100％充电）。访问此属性之前，请确保已启用电池监视。如果未启用电池监视，则电池状态为UIDevice.BatteryState.unknown，此属性的值为–1.0。
var batteryLevel: Float { UIDevice.current.batteryLevel }要监视设备的电池电量，您可以添加观察者
UIDevice.batteryLevelDidChangeNotification：
NotificationCenter.default.addObserver(self, selector: #selector(batteryLevelDidChange), name: UIDevice.batteryLevelDidChangeNotification, object: nil)
@objc func batteryLevelDidChange(_ notification: Notification) { print(batteryLevel)}您还可以验证电池状态：
var batteryState: UIDevice.BatteryState { UIDevice.current.batteryState }case .unknown // "The battery state for the device cannot be determined."case .unplugged // "The device is not plugged into power; the battery is discharging"case .charging // "The device is plugged into power and the battery is less than 100% charged."case .full // "The device is plugged into power and the battery is 100% charged."
并添加观察者
UIDevice.batteryStateDidChangeNotification：
NotificationCenter.default.addObserver(self, selector: #selector(batteryStateDidChange), name: UIDevice.batteryStateDidChangeNotification, object: nil)
@objc func batteryStateDidChange(_ notification: Notification) { switch batteryState { case .unplugged, .unknown: print("not charging") case .charging, .full: print("charging or full") }}
