flutter - 我如何在 flutter 中听取 UIApplication 生命周期 iOS

Question

我想检测我的 iOS 应用写入 flutter 移动到后台并进入前台。我习惯于 WidgetsBindingObserver 来监听 flutter 中的生命周期。但它并不完全符合我的期望。当我在 flutter app lifecycle trigger AppLifecycleState.paused 中推送 native Controller 时，但我的应用程序正在运行。有人刚遇到这个问题吗？以及你解决问题的方式。谢谢

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    super.didChangeAppLifecycleState(state);
    if(state == AppLifecycleState.paused) {
      _viewModel.applicationMoveToBackground();

    } else if(state == AppLifecycleState.resumed) {
      _viewModel.applicationMoveToForeground();
    }
  }

Answer 1

我通过使用 FlutterBasicMessageChannel 发出 iOS UIApplication 生命周期来 flutter 解决了这个问题。在 iOS Runner 应用中:

import UIKit
import Flutter

@UIApplicationMain@objc class AppDelegate: FlutterAppDelegate {

    var applicationLifeCycleChannel: FlutterBasicMessageChannel!

    override func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        GeneratedPluginRegistrant.register(with: self)

        applicationLifeCycleChannel = FlutterBasicMessageChannel(
            name: "applicationLifeCycle",
            binaryMessenger: (window.rootViewController as! FlutterViewController).binaryMessenger,
            codec: FlutterStringCodec.sharedInstance())
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }

    override func applicationWillTerminate(_ application: UIApplication) {
        applicationLifeCycleChannel.sendMessage("applicationWillTerminate")
    }

    override func applicationWillEnterForeground(_ application: UIApplication) {
        applicationLifeCycleChannel.sendMessage("applicationWillEnterForeground")
    }

    override func applicationDidEnterBackground(_ application: UIApplication) {
        applicationLifeCycleChannel.sendMessage("applicationDidEnterBackground")
    }
}

在 Flutter 应用中:

 static const applicationLifecycleChannel = BasicMessageChannel<String>('applicationLifeCycle', StringCodec());
static const kApplicationWillTerminate = 'applicationWillTerminate';
  static const kApplicationWillEnterForeground = 'applicationWillEnterForeground';
  static const kApplicationDidEnterBackground = 'applicationDidEnterBackground';

  @override
  void initState() {
    applicationLifecycleChannel.setMessageHandler((message) async {
      switch(message) {
        case kApplicationWillTerminate:
          break;
        case kApplicationWillEnterForeground:
          _viewModel.applicationMoveToForeground();
          break;
        case kApplicationDidEnterBackground:
          _viewModel.applicationMoveToBackground();
          break;
        default:
          break;
      }
      return message;
    });
    super.initState();
  }