flutter create --template=plugin -i objc -a java platform_view

import 'package:flutter/material.dart';import 'package:flutter/services.dart';
const String singleColor = "singleColor";
class ColorView extends StatefulWidget {  @override  _ColorViewState createState() => _ColorViewState();}
class _ColorViewState extends State<ColorView> {  /// 平台通道,消息使用平台通道在客户端（UI）和宿主（平台）之间传递  MethodChannel _channel;
  @override  Widget build(BuildContext context) {    return UiKitView(      // 视图类型，作为唯一标识符      viewType: singleColor,      // 创建参数：将会传递给 iOS 端侧, 可以传递任意类型参数      creationParams: "yellow",      // 用于将creationParams编码后再发送到平台端。      // 这里使用Flutter标准二进制编码      creationParamsCodec: StandardMessageCodec(),      // 原生视图创建回调      onPlatformViewCreated: _onPlatformViewCreated,    );  }
  /// 原生视图创建回调操作  /// id 是原生视图唯一标识符  void _onPlatformViewCreated(int id) {    // 每个 id 对应创建唯一的平台通道    _channel = MethodChannel('singleColor_$id');    // 设置平台通道的响应函数    _channel.setMethodCallHandler(_handleMethod);  }
  /// 平台通道的响应函数  Future<void> _handleMethod(MethodCall call) async {    /// 视图没被装载的情况不响应操作    if (!mounted) {      return Future.value();    }    switch (call.method) {      default:        throw UnsupportedError("Unrecognized method");    }  }}

cd platform_view/example; flutter build ios --debug --no-codesign

Pods/Development Pods/platform_view/../../example/ios/.symlinks/plugins/platform_view/ios/Classes

#import "PlatformViewPlugin.h"#import "PlatfromViewFactory.h"
@implementation PlatformViewPlugin
/// 注册插件/// @param registrar 提供应用程序上下文和注册回调的方法+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {    // 注册视图工厂    // 绑定工厂唯一标识符这里与 Flutter UIKitView 所使用 viewType 一致    [registrar registerViewFactory:[[PlatfromViewFactory alloc] initWithMessenger:[registrar messenger]]                            withId:@"singleColor"];}
@end

#import <Foundation/Foundation.h>#import <Flutter/Flutter.h>
NS_ASSUME_NONNULL_BEGIN
@interface PlatfromViewFactory : NSObject<FlutterPlatformViewFactory>
/// 初始化视图工厂/// @param messager 用于与 Flutter 传输二进制消息通信- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger> *)messager;
@end
NS_ASSUME_NONNULL_END

#import "PlatfromViewFactory.h"#import "PlatformView.h"
@interface PlatfromViewFactory ()
/// 用于与 Flutter 传输二进制消息通信@property (nonatomic, strong) NSObject<FlutterBinaryMessenger> *messenger;
@end
@implementation PlatfromViewFactory
- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger> *)messager {    self = [super init];    if (self) {        self.messenger = messager;    }    return self;}
#pragma mark - FlutterPlatformViewFactory
/// 创建一个“FlutterPlatformView”/// 由iOS代码实现，该代码公开了一个用于嵌入Flutter应用程序的“UIView”。/// 这个方法的实现应该创建一个新的“UIView”并返回它。/// @param frame Flutter通过其布局widget来计算得来/// @param viewId 视图的唯一标识符，创建一个 UIKitView 该值会+1/// @param args 对应Flutter 端UIKitView的creationParams参数- (nonnull NSObject<FlutterPlatformView> *)createWithFrame:(CGRect)frame                                            viewIdentifier:(int64_t)viewId                                                 arguments:(id _Nullable)args {    PlatformView *platformView = [[PlatformView alloc] initWithWithFrame:frame                                                          viewIdentifier:viewId                                                               arguments:args                                                         binaryMessenger:self.messenger];    return platformView;}
/// 使用Flutter标准二进制编码- (NSObject<FlutterMessageCodec> *)createArgsCodec {    return [FlutterStandardMessageCodec sharedInstance];}
@end

#import <Foundation/Foundation.h>#import <Flutter/Flutter.h>
NS_ASSUME_NONNULL_BEGIN
@interface PlatformView : NSObject<FlutterPlatformView>
- (instancetype)initWithWithFrame:(CGRect)frame                   viewIdentifier:(int64_t)viewId                        arguments:(id _Nullable)args                  binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;
@end
NS_ASSUME_NONNULL_END

#import "PlatformView.h"
@interface PlatformView ()
/// 视图@property (nonatomic, strong) UIView *yellowView;
/// 平台通道@property (nonatomic, strong) FlutterMethodChannel *channel;
@end
@implementation PlatformView
- (instancetype)initWithWithFrame:(CGRect)frame                   viewIdentifier:(int64_t)viewId                        arguments:(id _Nullable)args                  binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {    if ([super init]) {        /// 初始化视图        self.yellowView = [[UIView alloc] init];        self.yellowView.backgroundColor = UIColor.yellowColor;                /// 这里的channelName是和Flutter 创建MethodChannel时的名字保持一致的，保证一个原生视图有一个平台通道传递消息        NSString *channelName = [NSString stringWithFormat:@"singleColor_%lld", viewId];        self.channel = [FlutterMethodChannel methodChannelWithName:channelName binaryMessenger:messenger];        // 处理 Flutter 发送的消息事件        [self.channel setMethodCallHandler:^(FlutterMethodCall *call, FlutterResult result) {            if ([call.method isEqualToString:@""]) {                            }        }];    }    return self;}
#pragma mark - FlutterPlatformView/// 返回真正的视图- (UIView *)view {    return self.yellowView;}
@end

import 'package:flutter/material.dart';import 'package:platform_view/color_view.dart';
void main() => runApp(MyApp());
class MyApp extends StatefulWidget {  @override  _MyAppState createState() => _MyAppState();}
class _MyAppState extends State<MyApp> {  @override  Widget build(BuildContext context) {    return MaterialApp(      home: Scaffold(        appBar: AppBar(          title: const Text('PlatformView Plugin'),        ),        body: Center(          // 由于原生视图的大小由父 Widget 决定,          // 这里添加 Container 作为父 Widget 并设置宽高为 100          child: Container(            width: 100.0,            height: 100.0,            child: ColorView(),          ),        ),      ),    );  }}

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

// The name of the Info.plist flag to enable the embedded iOS views preview.const char* const kEmbeddedViewsPreview = "io.flutter.embedded_views_preview";
bool IsIosEmbeddedViewsPreviewEnabled() {  return [[[NSBundle mainBundle] objectForInfoDictionaryKey:@(kEmbeddedViewsPreview)] boolValue];}

ExternalViewEmbedder* IOSSurfaceSoftware::GetExternalViewEmbedder() {  if (IsIosEmbeddedViewsPreviewEnabled()) {    return this;  } else {    return nullptr;  }}

if (flutter::IsIosEmbeddedViewsPreviewEnabled()) {    // Embedded views requires the gpu and the platform views to be the same.    // The plan is to eventually dynamically merge the threads when there's a    // platform view in the layer tree.    // For now we use a fixed thread configuration with the same thread used as the    // gpu and platform task runner.    // TODO(amirh/chinmaygarde): remove this, and dynamically change the thread configuration.    // https://github.com/flutter/flutter/issues/23975
    flutter::TaskRunners task_runners(threadLabel.UTF8String,                          // label                                      fml::MessageLoop::GetCurrent().GetTaskRunner(),  // platform                                      fml::MessageLoop::GetCurrent().GetTaskRunner(),  // gpu                                      _threadHost.ui_thread->GetTaskRunner(),          // ui                                      _threadHost.io_thread->GetTaskRunner()           // io    );    // Create the shell. This is a blocking operation.    _shell = flutter::Shell::Create(std::move(task_runners),  // task runners                                    std::move(settings),      // settings                                    on_create_platform_view,  // platform view creation                                    on_create_rasterizer      // rasterzier creation    );  } else {    flutter::TaskRunners task_runners(threadLabel.UTF8String,                          // label                                      fml::MessageLoop::GetCurrent().GetTaskRunner(),  // platform                                      _threadHost.gpu_thread->GetTaskRunner(),         // gpu                                      _threadHost.ui_thread->GetTaskRunner(),          // ui                                      _threadHost.io_thread->GetTaskRunner()           // io    );    // Create the shell. This is a blocking operation.    _shell = flutter::Shell::Create(std::move(task_runners),  // task runners                                    std::move(settings),      // settings                                    on_create_platform_view,  // platform view creation                                    on_create_rasterizer      // rasterzier creation    );  }

void FlutterPlatformViewsController::OnCreate(FlutterMethodCall* call, FlutterResult& result) {  ...  NSDictionary<NSString*, id>* args = [call arguments];  // 获取 viewid  long viewId = [args[@"id"] longValue];  // 获取 viewType  std::string viewType([args[@"viewType"] UTF8String]);  ...  // 通过 viewType 获取视图工厂  NSObject<FlutterPlatformViewFactory>* factory = factories_[viewType].get();  ...  id params = nil;  // 解码参数  if ([factory respondsToSelector:@selector(createArgsCodec)]) {    NSObject<FlutterMessageCodec>* codec = [factory createArgsCodec];    if (codec != nil && args[@"params"] != nil) {      FlutterStandardTypedData* paramsData = args[@"params"];      params = [codec decode:paramsData.data];    }  }  // 通过视图工厂创建嵌入视图  NSObject<FlutterPlatformView>* embedded_view = [factory createWithFrame:CGRectZero                                                           viewIdentifier:viewId                                                                arguments:params];  views_[viewId] = fml::scoped_nsobject<NSObject<FlutterPlatformView>>([embedded_view retain]);
  // 将嵌入视图添加到FlutterTouchInterceptingView中，  // FlutterTouchInterceptingView主要负责处理手势转发和拒绝部分手势，  FlutterTouchInterceptingView* touch_interceptor = [[[FlutterTouchInterceptingView alloc]       initWithEmbeddedView:embedded_view.view      flutterViewController:flutter_view_controller_.get()] autorelease];
  // 存储视图  touch_interceptors_[viewId] =      fml::scoped_nsobject<FlutterTouchInterceptingView>([touch_interceptor retain]);  root_views_[viewId] = fml::scoped_nsobject<UIView>([touch_interceptor retain]);
  result(nil);}