标签: flutter-add-to-app

我已经使用缓存的颤振引擎进入了现有的本机应用程序（添加到应用程序）。

override fun onCreate(savedInstanceState: Bundle?) {
        Log.d(TAG, "onCreate")
        
        
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)
        context = this.application.applicationContext
        if (!FlutterEngineCache.getInstance().contains(
                FLUTTER_ENGINE
            )
        ) {
            mFlutterEngine = FlutterEngine(context)
            mFlutterEngine.dartExecutor
                .executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
            FlutterEngineCache.getInstance()
                .put(FLUTTER_ENGINE, mFlutterEngine)
        }
        //Create Flutter Fragment
        mFragmentManager = supportFragmentManager
        mFlutterFragment = mFragmentManager.findFragmentByTag(FLUTTER_FRAGMENT) as FlutterFragment?
        if (mFlutterFragment == null) {
            mFlutterFragment =
                FlutterFragment.withCachedEngine(FLUTTER_ENGINE).transparencyMode(FlutterView.TransparencyMode.opaque).build()
            mFragmentManager
                .beginTransaction()
                .add(R.id.fragment_container, mFlutterFragment as Fragment, FLUTTER_FRAGMENT)
                .commit()
        } else {
            mFragmentManager
                .beginTransaction()
                .show(mFragmentManager.findFragmentByTag(FLUTTER_FRAGMENT)!!)
                .commit()
        }
}

我在生产应用程序中遇到以下崩溃

  Caused by: java.lang.IllegalStateException: The requested cached FlutterEngine did not exist in the FlutterEngineCache: 'FLUTTER_ENGINE'
        at …

我已将颤振添加到现有的 Android 应用程序中。使用预热颤振引擎。

var flutterEngine = FlutterEngineCache.getInstance().get(Constants.FLUTTER_ENGINE)

        if (flutterEngine == null) {
            flutterEngine = FlutterEngine(this)
            FlutterEngineCache.getInstance().put(Constants.FLUTTER_ENGINE, flutterEngine)
            flutterEngine.navigationChannel.setInitialRoute(
                "route1"
            )
            flutterEngine.dartExecutor.executeDartEntrypoint(
                DartExecutor.DartEntrypoint.createDefault()
            )
        }

当我销毁颤振引擎时， FlutterEngineCache.getInstance().get(Constants.FLUTTER_ENGINE)?.destroy() 出现以下错误。

java.lang.RuntimeException: Unable to destroy activity: java.lang.RuntimeException: Cannot execute operation because FlutterJNI is not attached to native.

  Caused by: java.lang.RuntimeException: Cannot execute operation because FlutterJNI is not attached to native.
        at io.flutter.embedding.engine.FlutterJNI.ensureAttachedToNative(FlutterJNI.java:222)
        at io.flutter.embedding.engine.FlutterJNI.onSurfaceDestroyed(FlutterJNI.java:315)
        at io.flutter.embedding.engine.renderer.FlutterRenderer.stopRenderingToSurface(FlutterRenderer.java:207)
        at io.flutter.embedding.android.FlutterView.detachFromFlutterEngine(FlutterView.java:795)
        at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onDestroyView(FlutterActivityAndFragmentDelegate.java:442)
        at

所以我试图在单击按钮时打开一个简单的网络视图。

这是我的 Scaffold 小部件的主体：

body: 
WebView(
    initialUrl: "https://www.google.com/",
    javascriptMode: JavascriptMode.unrestricted,
)

有趣的是，当我独立运行这个 flutter 项目时，它成功地在 iOS 模拟器中打开了 Webview。但是当我将此 flutter 模块集成到现有的 iOS 应用程序中时，它不起作用（显示空白屏幕）。为了添加颤振模块，我遵循了此链接，模块的其他部分工作正常。

我已经在 flutter 模块的 info.plist 中设置了这个：

<key>io.flutter.embedded_views_preview</key>
<true/>

我在文件中添加了以下版本pubspec.yaml：

webview_flutter: ^0.3.22+1

我能找到的 Flutter 的 Add-to-App 的所有文档都演示了如何推送/继续/呈现新创建的 FlutterViewController。我需要将颤动视图添加到选项卡栏中的选项卡。我尝试将班级的超类更改为UIViewController有效FlutterViewController，但没有使用应用程序委托中创建的颤动引擎。此解决方案导致在启动屏幕中显示颤动视图之前，这是不希望的。

如何向 中添加颤动视图UIViewController？或者如何将引擎分配给FlutterViewController类内的引擎？