Inactive — 本质，Active 和 Background 之间的过渡状态

import UIKit

extension Notification.Name {
    static let systemInterruptionBegan = Notification.Name("systemInterruptionBegan")
    static let systemInterruptionEnded = Notification.Name("systemInterruptionEnded")
}

@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    func applicationWillResignActive(_ application: UIApplication) {
        // 应用程序进入 Inactive — 系统中断
        print("中断：Control Center、来电或系统警报")

        // 暂停时间敏感的操作
        pauseVideoPlayback()
        stopContinuousDataCollection()
        hideSensitiveInformation()

        // 通知组件
        NotificationCenter.default.post(name: .systemInterruptionBegan, object: nil)
    }

    // 从 Inactive 返回 Active
    func applicationDidBecomeActive(_ application: UIApplication) {
        resumeVideoPlayback()
        restartDataCollection()
        NotificationCenter.default.post(name: .systemInterruptionEnded, object: nil)
    }

    private func pauseVideoPlayback() {
        // 暂停视频以避免音频重叠
    }

    private func hideSensitiveInformation() {
        // 在屏幕截图时隐藏敏感数据
        // Control Center/App Switcher 截取 UI 屏幕截图
    }
}

import UIKit

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    // 场景变为非活动状态
    func sceneWillResignActive(_ scene: UIScene) {
        // 在 iPad 上，此场景失去焦点，但其他场景可能仍处于活动状态
        print("场景失去活动状态")

        // 暂停此场景的任务
        pauseSceneSpecificOperations()
    }

    // 场景变为活动状态
    func sceneDidBecomeActive(_ scene: UIScene) {
        print("场景已变为活动状态")
        resumeSceneSpecificOperations()
    }

    private func pauseSceneSpecificOperations() {
        // 暂停特定于此场景的操作
    }

    private func resumeSceneSpecificOperations() {
        // 焦点返回时恢复操作
    }
}

// AppDelegate 仍然是入口点，委托给场景
@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(
        _ application: UIApplication,
        configurationForConnecting connectingSceneSession: UISceneSession,
        options: UIScene.ConnectionOptions
    ) -> UISceneConfiguration {
        return UISceneConfiguration(
            name: "Default Configuration",
            sessionRole: connectingSceneSession.role
        )
    }
}

class VideoPlayerActivity : AppCompatActivity() {

    private var exoPlayer: ExoPlayer? = null
    private var currentPosition: Long = 0L

    override fun onPause() {
        super.onPause()
        // 应用程序失去焦点 — 暂停视频播放
        exoPlayer?.let { player ->
            if (player.isPlaying) {
                currentPosition = player.currentPosition
                player.pause()
            }
        }
        // 隐藏敏感数据（GDPR/银行界面）
        if (window.decorView.systemUiVisibility and
            View.SYSTEM_UI_FLAG_SECURE == 0
        ) {
            hideSensitiveOverlay()
        }
    }

    override fun onResume() {
        super.onResume()
        // 焦点返回 — 恢复播放
        exoPlayer?.seekTo(currentPosition)
        exoPlayer?.play()
        showSensitiveOverlay()
    }

    private fun hideSensitiveOverlay() {
        // 在财务数据上叠加黑屏
    }
}

import UIKit

final class SecureOverlayManager {
    private var blurView: UIVisualEffectView?

    func showBlurOverlay() {
        guard let window = UIApplication.shared.keyWindow,
              blurView == nil
        else { return }

        let blur = UIVisualEffectView(effect: UIBlurEffect(style: .dark))
        blur.frame = window.bounds
        blur.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        window.addSubview(blur)
        blurView = blur
    }

    func removeBlurOverlay() {
        blurView?.removeFromSuperview()
        blurView = nil
    }
}

// 在 AppDelegate 中的使用
func applicationWillResignActive(_ application: UIApplication) {
    SecureOverlayManager().showBlurOverlay()
}

func applicationDidBecomeActive(_ application: UIApplication) {
    SecureOverlayManager().removeBlurOverlay()
}