Flutter嵌套原生View。
还是最近的工作内容，把原生直播播放器嵌套到flutter内，引出的东西。

本篇通过这个需求，引出牵扯的东西吧。
如果要把原生组件嵌套到flutter中，那么我们需要认识一下下面几个东西。
FlutterPlugin
注册FlutterPlatformViewFactory对象的方法

/**
 * Registers a `FlutterPlatformViewFactory` for creation of platform views.
 *
 * Plugins can expose a `UIView` for embedding in Flutter apps by registering a view factory.
 *
 * @param factory The view factory that will be registered.
 * @param factoryId A unique identifier for the factory, the Dart code of the Flutter app can use
 *   this identifier to request creation of a `UIView` by the registered factory.
 * @param gestureRecognizersBlockingPolicy How UIGestureRecognizers on the platform views are
 * blocked.
 *
 */
- (void)registerViewFactory:(NSObject<FlutterPlatformViewFactory>*)factory
                     withId:(NSString*)factoryId;

FlutterPlatformViewFactory负责嵌套原生的工厂类。

FLUTTER_DARWIN_EXPORT
@protocol FlutterPlatformViewFactory <NSObject>
/**
 * Create a `FlutterPlatformView`.
 *
 * Implemented by iOS code that expose a `UIView` for embedding in a Flutter app.
 *
 * The implementation of this method should create a new `UIView` and return it.
 *
 * @param frame The rectangle for the newly created `UIView` measured in points.
 * @param viewId A unique identifier for this `UIView`.
 * @param args Parameters for creating the `UIView` sent from the Dart side of the Flutter app.
 *   If `createArgsCodec` is not implemented, or if no creation arguments were sent from the �Dart
 *   code, this will be null. Otherwise this will be the value sent from the Dart code as decoded by
 *   `createArgsCodec`.
 */
- (NSObject<FlutterPlatformView>*)createWithFrame:(CGRect)frame
                                   viewIdentifier:(int64_t)viewId
                                        arguments:(id _Nullable)args;

/**
 * Returns the `FlutterMessageCodec` for decoding the args parameter of `createWithFrame`.
 *
 * Only needs to be implemented if `createWithFrame` needs an arguments parameter.
 */
@optional
- (NSObject<FlutterMessageCodec>*)createArgsCodec;
@end

FlutterPlatformView 包裹原生组件的flutterView

@protocol FlutterPlatformView <NSObject>
/**
 * Returns a reference to the `UIView` that is wrapped by this `FlutterPlatformView`.
 */
- (UIView*)view;
@end

答题的思路在于，通过FlutterPlatformViewFactory协议，来创建工厂对象，并通过工厂类的create方法，创建嵌套原生的flutterView。

// 直播播放器
public class ZLFlutterRTCLivePlayViewFactory : NSObject,FlutterPlatformViewFactory{
    
    public static let SIGN = "ZLFlutterRTCLivePlayView";
    private var message : FlutterBinaryMessenger;
    
    init(message : FlutterBinaryMessenger) {
        self.message = message;
    }
    
    public func create(withFrame frame: CGRect, viewIdentifier viewId: Int64, arguments args: Any?) -> FlutterPlatformView {
        // 绑定方法监听
        let channel = FlutterMethodChannel(
            name: "\(ZLFlutterRTCLivePlayViewFactory.SIGN)_\(viewId)",
            binaryMessenger: message
        )
        let view = ZLFlutterRTCLivePlayView(frame, channel: channel);
        channel.setMethodCallHandler(view.handle);
        return view;
    }
}

class ZLFlutterRTCLivePlayView : NSObject,FlutterPlatformView{
    private lazy var playView : UIView = {
        return UIView();
    }(); // 播放View
    private var frame: CGRect?;
    private var channel: FlutterMethodChannel?
    
    private lazy var player: TXLivePlayer = { // 播放器
        let livePlayer = TXLivePlayer()
        livePlayer.delegate = self
        return livePlayer
    }()
    
    init(_ frame : CGRect, channel: FlutterMethodChannel?) {
        super.init()
        self.frame = frame;
        self.channel = channel;
    }
    
    public func view() -> UIView {
        return playView;
    }

    public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        switch call.method {
        case "startPlay":
            startPlay(call, result: result);
            break;
        case "stopPlay":
            stopPlay(call, result: result);
            break;
        case "setMute":
            setMute(call, result: result);
            break;
        case "setRenderMode":
            setRenderMode(call, result: result);
            break;
        case "setRenderRotation":
            setRenderRotation(call, result: result);
            break;
        default:
            result(FlutterMethodNotImplemented);
        }
    }
    
    private func startPlay(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        if let url = CommonUtils.getParamByKey(call: call, result: result, param: "url") as? String,
           let type = CommonUtils.getParamByKey(call: call, result: result, param: "type") as? Int,
           let playType = TX_Enum_PlayType(rawValue: type) {
            player.setupVideoWidget(frame ?? CGRect.zero, contain: self.playView, insert: 0)
            player.startPlay(url, type: .PLAY_TYPE_VOD_HLS)
        }
        result(nil)
    }
    
    private func stopPlay(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        player.stopPlay()
        player.removeVideoWidget()
        result(nil)
    }
    
    private func setMute(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        if let mute = CommonUtils.getParamByKey(call: call, result: result, param: "url") as? Bool {
            player.setMute(mute)
        }
        
        result(nil)
    }
    
    private func setRenderMode(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        if let value = CommonUtils.getParamByKey(call: call, result: result, param: "renderMode") as? Int,
           let renderMode = TX_Enum_Type_RenderMode.init(rawValue: value) {
            self.player.setRenderMode(renderMode)
        }
        
        result(nil)
    }
    
    private func setRenderRotation(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        if let value = CommonUtils.getParamByKey(call: call, result: result, param: "rotation") as? Int,
           let rotation = TX_Enum_Type_HomeOrientation.init(rawValue: value) {
            self.player.setRenderRotation(rotation)
        }
        
        result(nil)
    }
}

通过FlutterPlugin来注册工厂类。

public static func register(with registrar: FlutterPluginRegistrar) {
        // 直播播放器
        let playViewFactory = ZLFlutterRTCLivePlayViewFactory(message: registrar.messenger());
        registrar.register(
            playViewFactory,
            withId: ZLFlutterRTCLivePlayViewFactory.SIGN
        );
    }

对于flutter端的代码,通过channelType来进行原生flutter的交互。

/// 直播播放器
class ZLPlayView extends StatefulWidget {
  /// @nodoc
  /// channel标识符
  static String channelType = "ZLFlutterRTCLivePlayView";
  final ValueChanged<int>? onViewCreated;
  final Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers;
  const ZLPlayView({Key? key, this.onViewCreated, this.gestureRecognizers})
      : super(key: key);

  @override
  State<StatefulWidget> createState() => ZLPlayViewState();
}

//// @nodoc
class ZLPlayViewState extends State<ZLPlayView> {
  @override
  Widget build(BuildContext context) {
    if (Platform.isAndroid) {
      return AndroidView(
        viewType: ZLPlayView.channelType,
        onPlatformViewCreated: _onPlatformViewCreated,
        gestureRecognizers: widget.gestureRecognizers,
      );
    } else if (Platform.isIOS) {
      return UiKitView(
        viewType: ZLPlayView.channelType,
        onPlatformViewCreated: _onPlatformViewCreated,
        gestureRecognizers: widget.gestureRecognizers,
      );
    } else {
      return Text("该平台不支持Platform View");
    }
  }

  void _onPlatformViewCreated(int id) {
    if (widget.onViewCreated != null) {
      widget.onViewCreated!(id);
    }
  }
}

typedef ZLPlayOnPlayEvent = void Function(int id, Map param);

/// @nodoc
/// Weex页面控制器方法
class ZLPlayViewController {
  late final MethodChannel _channel;
  ZLPlayOnPlayEvent? _onPlayEvent;

  ZLPlayViewController(int id) {
    _channel = new MethodChannel(ZLPlayView.channelType + '_$id');
    _channel.setMethodCallHandler((methodCall) async {
      switch (methodCall.method) {
        case 'onPlayEvent':
          int id = methodCall.arguments['EvtID'] ?? 0;
          Map param = methodCall.arguments['param'] ?? {};
          if (_onPlayEvent != null) {
            _onPlayEvent!(id, param);
          }
          throw MissingPluginException();
        case 'onNetStatus':
          throw MissingPluginException();
        default:
          throw MissingPluginException();
      }
    });
  }

  setOnPlayEvent(ZLPlayOnPlayEvent onPlayEvent) {
    _onPlayEvent = onPlayEvent;
  }

  /// @description: 开始播放
  /// @param url: 播放地址
  /// @param type: 播放类型
  /// @return void
  Future<void> startPlay(String url, ZLPlayType type) {
    return _channel.invokeMethod('startPlay', {"url": url, "type": type.index});
  }

  /// @description: 停止播放
  /// @return void
  Future<void> stopPlay() {
    return _channel.invokeMethod('stopPlay');
  }

  /// @description: 设置静音
  /// @param mute: true 静音
  /// @return void
  Future<void> setMute(bool mute) {
    return _channel.invokeMethod('setMute', {"mute": mute});
  }

  /// @description: 设置画面的裁剪模式
  /// @param setRenderMode: 模式
  /// @return void
  Future<void> setRenderMode(ZLPlayViewRenderMode renderMode) {
    return _channel
        .invokeMethod('setRenderMode', {"renderMode": renderMode.index});
  }

  /// @description: 设置画面的方向
  /// @param rotation: 方向
  /// @return void
  Future<void> setRenderRotation(ZLPlayViewHomeOrientation rotation) {
    return _channel
        .invokeMethod('setRenderRotation', {"rotation": rotation.index});
  }
}

如果使用的话，最好在外面再套一层业务层来使用。

class ZLLiveRoomVideoView extends ZLPlayView {
  const ZLLiveRoomVideoView(
      {Key? key,
      // int? viewType,
      ValueChanged<int>? onViewCreated,
      Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers})
      : super(
            key: key,
            onViewCreated: onViewCreated,
            gestureRecognizers: gestureRecognizers);
}