如何在颤动中收听 UIApplication 生命周期 iOS答案

【问题标题】：How can I listen UIApplication lifecycle iOS in flutter如何在颤动中收听 UIApplication 生命周期 iOS
【发布时间】：2019-09-23 15:25:07
【问题描述】：

我想检测我的 iOS 应用程序写入时颤动移动到后台并进入前台。我习惯 WidgetsBindingObserver 来听生命周期的颤动。但它并不完全不是我的期望。当我在颤振应用程序生命周期触发器中推送本机控制器时 AppLifecycleState.paused 但我的应用程序正在运行。有人刚刚遇到过这个问题吗？以及您解决问题的方式。谢谢

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

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

【问题讨论】：

标签： flutter

【解决方案1】：

我通过使用 FlutterBasicMessageChannel 发出 iOS UIApplication 生命周期来颤振解决了这个问题。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();
  }

【讨论】：

【解决方案2】：

你在使用 WidgetsBindingObserver 吗？

class _PageState extends State<Page> with WidgetsBindingObserver {
    @override
    void initState() {
        super.initState();
        WidgetsBinding.instance.addObserver(this);
    }

    @override
    dispose() {
        super.dispose();
        WidgetsBinding.instance.removeObserver(this);
    }

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

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

【讨论】：

是的，我曾经在我的项目中使用上述代码，但是当我从诸如 Image Picker 之类的颤振中推送新的本机控制器时，我不希望应用程序移动到暂停状态。