FlutterBoost 实现Flutter页面内嵌iOS view

在使用Flutter混合开发中会遇到一些原生比Flutter优秀的控件，不想使用Flutter的控件，想在Flutter中使用原生控件。这时就会用到 Flutter页面中内嵌原生view，这里简单介绍一个内嵌 iOS 的view。

注：这里使用了 FlutterBoost。网上大部分都是代码执行不起来，本案例起码可以正常使用。

原生部分
这里开始在原生部分进行处理
自定义 view FlutterIosTextLabel

#import <Foundation/Foundation.h>
#import <Flutter/Flutter.h>

NS_ASSUME_NONNULL_BEGIN

@interface FlutterIosTextLabel : NSObject<FlutterPlatformView>

@property (nonatomic, strong) UILabel *label;


- (instancetype)initWithFrame:(CGRect)frame
               viewIdentifier:(int64_t)viewId
                    arguments:(id _Nullable)args
              binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;

@end

NS_ASSUME_NONNULL_END

#import "FlutterIosTextLabel.h"

@implementation FlutterIosTextLabel

//在这里只是创建了一个UILabel
- (instancetype)initWithFrame:(CGRect)frame viewIdentifier:(int64_t)viewId arguments:(id _Nullable)args binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
  if (self = [super init]) {
      self.label = [UILabel new];
      self.label.backgroundColor = [UIColor yellowColor];
      self.label.textColor = [UIColor redColor];
      self.label.textAlignment = NSTextAlignmentCenter;
      self.label.numberOfLines = 0;
      NSDictionary *dict = (NSDictionary *)args;
      NSString *textValue = dict[@"content"];
      self.label.text = [NSString stringWithFormat:@"我是iOSView \n在显示：%@", textValue];
  }
  return self;
}

- (nonnull UIView *)view {
    return self.label;
}

@end

创建 FlutterIosTextLabelFactory

#import <Foundation/Foundation.h>
#import <Flutter/Flutter.h>


NS_ASSUME_NONNULL_BEGIN

@interface FlutterIosTextLabelFactory : NSObject<FlutterPlatformViewFactory>

- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;


@end

NS_ASSUME_NONNULL_END

#import "FlutterIosTextLabelFactory.h"
#import "FlutterIosTextLabel.h"



@implementation FlutterIosTextLabelFactory
{
    NSObject<FlutterBinaryMessenger> *_messenger;
}

- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
  self = [super init];
  if (self) {
    _messenger = messenger;
  }
  return self;
}

- (NSObject<FlutterPlatformView>*)createWithFrame:(CGRect)frame viewIdentifier:(int64_t)viewId arguments:(id _Nullable)args {
  return [[FlutterIosTextLabel alloc] initWithFrame:frame viewIdentifier:viewId arguments:args binaryMessenger:_messenger];
}

-(NSObject<FlutterMessageCodec> *)createArgsCodec{
    return [FlutterStandardMessageCodec sharedInstance];
}

创建 FlutterIosTextLabelPlugin

#import <Foundation/Foundation.h>
#import <Flutter/Flutter.h>

NS_ASSUME_NONNULL_BEGIN

@interface FlutterIosTextLabelPlugin : NSObject<FlutterPlugin>
+ (void)registerWithRegistrar:(nonnull NSObject<FlutterPluginRegistrar> *)registrar;
@end

NS_ASSUME_NONNULL_END

#import "FlutterIosTextLabelPlugin.h"
#import "FlutterIosTextLabelFactory.h"

@implementation FlutterIosTextLabelPlugin

+ (void)registerWithRegistrar:(nonnull NSObject<FlutterPluginRegistrar> *)registrar {
    
    //注册插件
    //注册 FlutterIosTextLabelFactory
    //custom_platform_view 为flutter 调用此  textLabel 的标识
    [registrar registerViewFactory:[[FlutterIosTextLabelFactory alloc] initWithMessenger:registrar.messenger] withId:@"custom_platform_view"];
}
@end

到此原生已经集成完成一半，重点是接下来部分。

在 AppDelegate 中集成使用
修改AppDelegate.h：修改继承为FlutterAppDelegate，并删除window属性，因为FlutterAppDelegate中已经自带window属性

#import <UIKit/UIKit.h>
#import <Flutter/Flutter.h>

@interface AppDelegate : FlutterAppDelegate
@end

在AppDelegate.m中引入相关头文件

#import "FlutterIosTextLabel.h"
#import "GeneratedPluginRegistrant.h"
#import "FlutterIosTextLabelPlugin.h"

在AppDelegate.m中注册插件，在引入 flutter_boost的情况下，需要等 flutter_boost初始化完成后，用FlutterEngine对插件进行初始化。

@interface AppDelegate ()

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    HYFlutterBoostDelegate* delegate = [[HYFlutterBoostDelegate alloc]init];
    
    self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    self.window.backgroundColor = [UIColor whiteColor];
    
    
    HYTabBarController *tab = [[HYTabBarController alloc]init];

    self.window.rootViewController = tab;
    [self.window makeKeyAndVisible];
    
    
    [FlutterBoost.instance setup:application delegate:delegate callback:^(FlutterEngine *engine) {
        NSLog(@"FlutterBoost 开始操作");
        // 使用 MethodChannel
        [HYFlutterNavChannel start];
        [HYFlutterCommonChannel start];

        
        // 初始化Flutter内嵌iOSView插件
//        NSObject<FlutterPluginRegistrar> *registrar = [engine registrarForPlugin:@"custom_platform_view_plugin"];
//        FlutterIosTextLabelFactory *factory = [[FlutterIosTextLabelFactory alloc] initWithMessenger:registrar.messenger];
//        [registrar registerViewFactory:factory withId:@"custom_platform_view"];
        
        // 升级处理
        NSObject<FlutterPluginRegistrar> *registrar = [engine registrarForPlugin:@"custom_platform_view_plugin"];
        [FlutterIosTextLabelPlugin registerWithRegistrar:registrar];
        
    }];
    
    return YES;
}


@end

到此原生集成完毕，接下来在 Flutter中进行集成

Flutter 部分

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

class CMNativePage extends StatelessWidget {
  const CMNativePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("详情"),
      ),
      body: const Center(
        child: IOSCompositionWidget(),
      ),
    );
  }
}

class IOSCompositionWidget extends StatelessWidget {
  const IOSCompositionWidget({super.key});

  @override
  Widget build(BuildContext context) {
    // This is used in the platform side to register the view.
    const String viewType = 'custom_platform_view';
    // Pass parameters to the platform side.
    final Map<String, dynamic> creationParams = {
      'content': 'Flutter传给原生iOSView的参数'
    };

    return UiKitView(
      viewType: viewType,
      creationParams: creationParams,
      creationParamsCodec: const StandardMessageCodec(),
    );
  }
}

注册路由

static const String nativaPage = '/nativaPage';

 nativaPage: (settings, uniqued) {
      return MaterialPageRoute(
          settings: settings,
          builder: (_) {
            return const CMNativePage();
          });
    },

在Flutter地方使用

 TextButton(
            child: const Text("加载原生控件"),
            onPressed: () {
              BoostNavigator.instance
                  .push(HYRouter.nativaPage, arguments: {"home": "home页面传递数值"});
              // showBottomWidget(context, const CMNativePage());
            },
          ),

到此Flutter中也完成集成。
如果想要某些弹出样式，自己再进行处理。这里只是简单的使用Flutter 内嵌 iOS原生view。

注意事项：

FlutterIosTextLabelFactory中的createArgsCodec方法一定不能遗漏，否则会导致传值不成功。类型也一定要和Dart部分的native.dart->IOSCompositionWidget-> UiKitView-> creationParamsCodec保持一致。否则会导致崩溃。
使用官方文档中的写法是没有问题，但是本案例中使用了flutter_boost，再跟着官网集成就会出现问题。需要更flutter_boost初始化完成，再对FlutterEngine对插件进行初始化。
其中withId:xxx，xxx代表控件的ID，需要和Dart部分的IOSCompositionWidget中的viewType保持一致。命名为：custom_platform_view。
其中registrarForPlugin:xxx，xxx代表插件的ID。命名为：custom_platform_view_plugin。