在Flutter中使用Android、iOS的原生 View

我們在進行Flutter開發的時候，有時候是需要用到原生的View，比如WebView、MapView、第三方廣告SDK等，Flutter提供了AndroidView、UiKitView可以實現相關功能。

 

創建項目

這里以在Flutter顯示原生的TextView為案例，展示如何實現，創建項目過程這里不展示，建議使用Android Studio進行開發。

 

編寫平台相關的代碼

Android

創建PlatformView類

class AndroidTextView(context: Context) : PlatformView { val contentView: TextView = TextView(context) override fun getView(): View { return contentView } override fun dispose() {} } 

創建PlatformViewFactory類

class AndroidTextViewFactory : PlatformViewFactory(StandardMessageCodec.INSTANCE) {
    override fun create(context: Context, viewId: Int, args: Any?): PlatformView {
        val androidTextView = AndroidTextView(context)
        androidTextView.contentView.id = viewId
        val params = args?.let { args as Map<*, *> } val text = params?.get("text") as CharSequence? text?.let { androidTextView.contentView.text = it } return androidTextView } } 

注冊工廠，不同版本的注冊方式有所不同，這里是1.12.13版本

class MainActivity : FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine)
        val registry = flutterEngine.platformViewsController.registry
        registry.registerViewFactory("platform_text_view", AndroidTextViewFactory())
    }
}

iOS

第一步：在info.plist增加io.flutter.embedded_views_preview=true，至關重要。

第二步：創建 PlatformTextView.swift

import Foundation
import Flutter
class PlatformTextView: NSObject,FlutterPlatformView {
    let frame: CGRect;
    let viewId: Int64;
    var text:String = ""

    init(_ frame: CGRect,viewID: Int64,args :Any?) {
        self.frame = frame
        self.viewId = viewID
        if(args is NSDictionary){
            let dict = args as! NSDictionary
            self.text = dict.value(forKey: "text") as! String
        }
    }
    func view() -> UIView {
        let label = UILabel()
        label.text = self.text
        label.textColor = UIColor.red
        label.frame = self.frame
        return label
    }
}

第三步：創建PlatformTextViewFactory.swift

import Foundation import Flutter class PlatformTextViewFactory: NSObject,FlutterPlatformViewFactory { func create(withFrame frame: CGRect, viewIdentifier viewId: Int64, arguments args: Any?) -> FlutterPlatformView { return PlatformTextView(frame,viewID: viewId,args: args) } func createArgsCodec() -> FlutterMessageCodec & NSObjectProtocol { return FlutterStandardMessageCodec.sharedInstance() } } 

第四步：在 AppDelegate.swift 注冊

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)
    let factory = PlatformTextViewFactory()
    let registrar = self.registrar(forPlugin: "platform_text_view_plugin")
    registrar.register(factory, withId: "platform_text_view")
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

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編寫Flutter代碼

import 'package:flutter/foundation.dart'; import 'package:flutter/material.dart'; import 'package:flutter/services.dart'; void main() => runApp(MyApp()); class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Flutter Demo', theme: ThemeData( primarySwatch: Colors.blue, ), home: MyHomePage(title: 'Flutter Demo Home Page'), ); } } class MyHomePage extends StatefulWidget { MyHomePage({Key key, this.title}) : super(key: key); final String title; @override _MyHomePageState createState() => _MyHomePageState(); } class _MyHomePageState extends State<MyHomePage> { Widget getPlatformTextView() { if (defaultTargetPlatform == TargetPlatform.android) { return AndroidView( viewType: "platform_text_view", creationParams: <String, dynamic>{"text": "Android Text View"}, creationParamsCodec: const StandardMessageCodec()); } else if (defaultTargetPlatform == TargetPlatform.iOS) { return UiKitView( viewType: "platform_text_view", creationParams: <String, dynamic>{"text": "iOS Label"}, creationParamsCodec: const StandardMessageCodec()); } else { return Text("Not supported"); } } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text(widget.title), ), body:getPlatformTextView(), ); } }