swift - 观看操作系统 : Swift KVO for BatteryState is not working

Question

我想监控 watch 电池状态，所以我像这样为电池状态添加了 KVO

private func setupNotification() {

    WKInterfaceDevice.current().addObserver(self,
                                            forKeyPath: #keyPath(WKInterfaceDevice.batteryState),
                                            options: [.new],
                                            context: nil)
}

override public func observeValue(forKeyPath keyPath: String?,
                                  of object: Any?,
                                  change: [NSKeyValueChangeKey: Any]?,
                                  context: UnsafeMutableRawPointer?) {
    if keyPath == #keyPath(WKInterfaceDevice.batteryState) {
        switch WKInterfaceDevice.current().batteryState {
        case .charging:
            self.stopMonitoring()
        case .unplugged:
            if BatteryManager.batteryLevel > Constant.Battery.criticalValue {
                self.startMonitoring()
            }
        default:
            break
        }
    }
}

我之前也加过

func enableBatteryMonitoring() {
    WKInterfaceDevice.current().isBatteryMonitoringEnabled = true
}

但是当插入/拔出充电器时，它不会被调用。任何许可，否则我缺少什么？

Answer 1

据我所见，文档中没有明确说明此属性符合 KVO。
他们在 WatchKit 文档中说:

If battery monitoring is enabled, this property is set to a value between 0.0 (0% charge) and 1.0 (100% charge). When the batteryState property is set to WKInterfaceDeviceBatteryState.unknown (for example, when battery monitoring is disabled), the value is -1.0.

看来 isBatteryMonitoringEnabled 它只是让您能够通过询问其值(通过轮询)而不是观察它来读取电池。