耗电-定位与传感器优化

// Bad: 所有场景都用Best，页面打开就开，关闭不关
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.startUpdatingLocation()

// Bad: distanceFilter用kCLDistanceFilterNone，每次都回调
locationManager.distanceFilter = kCLDistanceFilterNone

class WeatherLocationClient: NSObject, CLLocationManagerDelegate {
    private let manager = CLLocationManager()
    private var completion: ((CLLocation) -> Void)?
    
    override init() {
        super.init()
        manager.delegate = self
        manager.desiredAccuracy = kCLLocationAccuracyKilometer
        manager.distanceFilter = 500   // 500米才更新
    }
    
    func requestOnce(_ completion: @escaping (CLLocation) -> Void) {
        self.completion = completion
        manager.requestLocation()  // 一次性定位，完成后自动停止
    }
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locs: [CLLocation]) {
        guard let loc = locs.last else { return }
        completion?(loc)
        completion = nil
    }
    
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        completion = nil
    }
}

// SignificantLocationChange：位置发生500m+变化或切换基站时唤起
manager.startMonitoringSignificantLocationChanges()

// Region Monitoring：进入/离开指定圆形区域时唤起
let region = CLCircularRegion(
    center: center,
    radius: 200,
    identifier: "home"
)
region.notifyOnEntry = true
region.notifyOnExit = true
manager.startMonitoring(for: region)

// Visits：系统判定"有意义的到访"时唤起
manager.startMonitoringVisits()

class TrackingSession {
    private let manager = CLLocationManager()
    
    func start() {
        manager.desiredAccuracy = kCLLocationAccuracyBest
        manager.distanceFilter = 20
        manager.allowsBackgroundLocationUpdates = true
        manager.pausesLocationUpdatesAutomatically = true  // 系统判定用户静止时自动暂停
        manager.activityType = .fitness                    // 让系统优化电池
        manager.startUpdatingLocation()
    }
    
    func stop() {
        manager.stopUpdatingLocation()
        manager.allowsBackgroundLocationUpdates = false
    }
}

if manager.accuracyAuthorization == .reducedAccuracy {
    manager.requestTemporaryFullAccuracyAuthorization(withPurposeKey: "Navigation") { error in
        // 用户选择后的回调
    }
}

let motionManager = CMMotionManager()
motionManager.deviceMotionUpdateInterval = 1.0 / 30.0  // 30Hz
motionManager.startDeviceMotionUpdates(to: .main) { motion, error in
    guard let m = motion else { return }
    // attitude, rotationRate, userAcceleration, gravity
}

// Bad: 100Hz采样，即使视图已经不可见
motionManager.accelerometerUpdateInterval = 0.01
motionManager.startAccelerometerUpdates(to: .main) { ... }

// Good: 按需采样
motionManager.deviceMotionUpdateInterval = 0.2  // 5Hz就够的场景别开更高

// Better: 页面消失时停止
override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    motionManager.stopDeviceMotionUpdates()
}

if #available(iOS 15.0, *) {
    let link = CADisplayLink(target: self, selector: #selector(tick))
    // 静态内容：10~30Hz就够
    link.preferredFrameRateRange = CAFrameRateRange(
        minimum: 10, maximum: 30, preferred: 20
    )
    link.add(to: .main, forMode: .common)
}

if #available(iOS 15.0, *) {
    view.window?.windowScene?.preferredFrameRateRange = 
        CAFrameRateRange(minimum: 10, maximum: 60, preferred: 30)
}

class EnergyPolicy {
    
    static var isLowPower: Bool {
        ProcessInfo.processInfo.isLowPowerModeEnabled
    }
    
    static func apply() {
        if isLowPower {
            // 降帧率
            ProMotionPolicy.capTo(30)
            // 关闭自动播放
            VideoAutoplayPolicy.disabled = true
            // 降精度定位
            LocationPolicy.accuracy = .kilometer
            // 关闭预加载
            PrefetchPolicy.enabled = false
            // 暂停非必要后台同步
            BackgroundSyncPolicy.paused = true
        }
    }
}

// 监听变化
NotificationCenter.default.addObserver(
    forName: .NSProcessInfoPowerStateDidChange,
    object: nil,
    queue: .main
) { _ in
    EnergyPolicy.apply()
}