flutter 与iOS混合开发

在Flutter项目开发中有时候有些常用的框架没有Flutter版本，这样的场景就需要接入原生sdk并完成与原生sdk通讯 这里主要讲解如何实现与iOS的混合开发
大致思路就是创建Flutter_module项目，并将Flutter项目以及引用的第三方库编译成静态Framework并在iOS中通过pod的方式引入

第一步：创建一个原生的iOS工程
1.创建一个空文件夹 名字叫 flutter_iOS_Mixture
2.在flutter_iOS_Mixture文件夹中创建XCode工程，并在工程中执行

pod init
pod install

第二步：创建Flutter_Module
1.定位到flutter_iOS_Mixture文件夹目录，并在终端执行命令，创建flutter module

flutter create -t module flutter_project

执行完毕后，工程中的目录结构
2.查看目录结构查看隐藏文件请使用快捷键打开隐藏文件

command + shift + .

目录结构

.
├── flutter_project
│   ├── README.md
│   ├── flutter_project.iml
│   ├── flutter_project_android.iml
│   ├── lib
│   ├── pubspec.lock
│   ├── pubspec.yaml
│   └── test
└── iOS_App
    ├── iOS_App
    ├── iOS_App.xcodeproj
    ├── iOS_AppTests
    └── iOS_AppUITests

3.打开Flutter工程，并在pubspec.yaml文件中添加两个第三方框架 执行 pub get

  cupertino_icons: ^0.1.2
  webview_flutter: ^0.3.19+9
  url_launcher: ^5.1.2

第三步：将Flutter编译成静态Framework并引用到iOS工程中
这里就有个分支了两种解决方案 1种是直接在iOS中添加依赖，就可以实现Flutter与iOS的混合，操作简单，但是有个缺点就是如果是多人开发项目的话，直接引入，需要每个开发者都需要有Flutter环境才可以正常编译通过，否则会报错，这样侵入性太强，但是如果开发人数少，使用这种方式确实可以提升开发效率(不能每次修改Flutter内容后都需要重新将Flutter打包成Framework，节约了不少时间)，这也是苹果官方推荐使用的解决方案
直接在Podfile文件中加入如果内容，Flutter与iOS的桥接就算完成了

flutter_application_path = '../flutter_project/'
load File.join(flutter_application_path, '.ios', 'Flutter', 'podhelper.rb')
install_all_flutter_pods(flutter_application_path)

全部文件如下：

# Uncomment the next line to define a global platform for your project
# platform :ios, '9.0'
flutter_application_path = '../flutter_project/'

load File.join(flutter_application_path, '.ios', 'Flutter', 'podhelper.rb')

target 'iOS_App' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!
  
  install_all_flutter_pods(flutter_application_path)

  # Pods for iOS_App

  target 'iOS_AppTests' do
    inherit! :search_paths
    # Pods for testing
  end

  target 'iOS_AppUITests' do
    # Pods for testing
  end

end

执行pod install将Flutter引入到iOS项目中

chenhaodeMac:iOS_App chenhao$ pod install
Analyzing dependencies
Downloading dependencies
Installing FlutterPluginRegistrant 0.0.1
Installing url_launcher (0.0.1)
Installing url_launcher_macos (0.0.1)
Installing url_launcher_web (0.0.1)
Installing webview_flutter (0.0.1)
Generating Pods project
Integrating client project
Pod installation complete! There are 7 dependencies from the Podfile and 7 total pods installed.

查看XCode工程发现导入的Flutter库也被加入到了iOS中

以上是Flutter与iOS桥接的第一种方式

2.将Flutter作为一个组件加入到iOS工程中，这样需要使用的时候，直接通过pod导入就行了，这样的好处是任何人都可以导入该插件，不需要电脑中装有Flutter环境，但是这种方式桥接操作相对繁杂，Flutter项目中内容有修改，需要重新打包并提交iOS工程中才可以生效，下面主要介绍这种方式如何实现与iOS的桥接
1> 创建一个Pod库在flutter_iOS_Mixture根目录执行命令创建pod lib

pod lib create flutter_lib

chenhaodeMac:flutter_iOS_ Mixture chenhao$ pod lib create flutter_lib
Cloning `https://github.com/CocoaPods/pod-template.git` into `flutter_lib`.
Configuring flutter_lib template.

To get you started we need to ask a few questions, this should only take a minute.

If this is your first time we recommend running through with the guide: 
 - https://guides.cocoapods.org/making/using-pod-lib-create.html
 ( hold cmd and double click links to open in a browser. )


What platform do you want to use?? [ iOS / macOS ]
 > iOS

What language do you want to use?? [ Swift / ObjC ]
 > ObjC

Would you like to include a demo application with your library? [ Yes / No ]
 > NO

Which testing frameworks will you use? [ Specta / Kiwi / None ]
 > None

Would you like to do view based testing? [ Yes / No ]
 > No 

What is your class prefix?
 > ASS 

Running pod install on your new library.

Analyzing dependencies
Downloading dependencies
Installing flutter_lib (0.1.0)
Generating Pods project
Integrating client project

[!] Please close any current Xcode sessions and use `flutter_lib.xcworkspace` for this project from now on.
Pod installation complete! There is 1 dependency from the Podfile and 1 total pod installed.
Ace! you're ready to go!

此时的目录结构如下

.
├── flutter_lib
│   ├── Example
│   ├── LICENSE
│   ├── README.md
│   ├── _Pods.xcodeproj -> Example/Pods/Pods.xcodeproj
│   ├── flutter_lib
│   └── flutter_lib.podspec
├── flutter_project
│   ├── README.md
│   ├── flutter_project.iml
│   ├── flutter_project_android.iml
│   ├── lib
│   ├── pubspec.lock
│   ├── pubspec.yaml
│   └── test
└── iOS_App
    ├── Podfile
    ├── Podfile.lock
    ├── Pods
    ├── iOS_App
    ├── iOS_App.xcodeproj
    ├── iOS_App.xcworkspace
    ├── iOS_AppTests
    └── iOS_AppUITests

在flutter_lib中创建ios_frameworks文件夹用来存放Flutter编译后的静态文件
找到flutter_lib中flutter_lib.podspec找打并修改引用 在文件最后添加如下一段代码

  s.ios.deployment_target = '8.0'

  s.static_framework = true
  p = Dir::open("ios_frameworks")
  arr = Array.new
  arr.push('ios_frameworks/*.framework')
  s.ios.vendored_frameworks = arr

  #s.source_files = 'flutter_lib/Classes/**/*'
  
  # s.resource_bundles = {
  #   'flutter_lib' => ['flutter_lib/Assets/*.png']
  # }

  # s.public_header_files = 'Pod/Classes/**/*.h'
  # s.frameworks = 'UIKit', 'MapKit'
  # s.dependency 'AFNetworking', '~> 2.3'

下面开始执行一段脚本 将Flutter编译并打包，将生成的frameworks自动移入到flutter_lib中的ios_frameworks中，这个ios_frameworks也正好是刚刚修改的flutter_lib.podspec引入的路径，将脚本放在flutter项目根目录中,脚本内容

if [ -z $out ]; then
    out='ios_frameworks'
fi

echo "准备输出所有文件到目录: $out"

echo "清除所有已编译文件"
find . -d -name build | xargs rm -rf
flutter clean
rm -rf $out
rm -rf build

flutter packages get

addFlag(){
    cat .ios/Podfile > tmp1.txt
    echo "use_frameworks!" >> tmp2.txt
    cat tmp1.txt >> tmp2.txt
    cat tmp2.txt > .ios/Podfile
    rm tmp1.txt tmp2.txt
}

echo "检查 .ios/Podfile文件状态"
a=$(cat .ios/Podfile)
if [[ $a == use* ]]; then
    echo '已经添加use_frameworks, 不再添加'
else
    echo '未添加use_frameworks,准备添加'
    addFlag
    echo "添加use_frameworks 完成"
fi

echo "编译flutter"
flutter build ios --debug --no-codesign
#flutter build ios --release --no-codesign

echo "编译flutter完成"
mkdir $out

cp -r build/ios/Debug-iphoneos/*/*.framework $out
#cp -r build/ios/Release-iphoneos/*/*.framework $out
cp -r .ios/Flutter/App.framework $out
cp -r .ios/Flutter/engine/Flutter.framework $out

echo "复制framework库到临时文件夹: $out"

libpath='../flutter_lib/'

rm -rf "$libpath/ios_frameworks"
mkdir $libpath
cp -r $out $libpath

echo "复制库文件到: $libpath"

执行脚本后发现flutter_lib中的ios_frameworks中多了一些flutter的使用的库文件

sh build_ios.sh

在podfile文件中引入组件化的flutter库

  pod 'flutter_lib', :path => '../flutter_lib'

执行pod install

chenhaodeMac:iOS_App chenhao$ pod install
Analyzing dependencies
Downloading dependencies
Installing flutter_lib (0.1.0)
Generating Pods project
Integrating client project
Pod installation complete! There is 1 dependency from the Podfile and 1 total pod installed.

此时Flutter与iOS的第二种桥接方式算是操作完了，此时flutter_lib已经通过pod引入到了项目中

第四步：iOS与Flutter互相通讯

1.iOS中调用Flutter工程

//初始化FlutterViewController
self.flutterViewController = [[FlutterViewController alloc] init];
//这里可以传递参数用来控制flutter做一些操作
[self.flutterViewController setInitialRoute:@"{"msg":"我是iOS传入的指令"}"];
self.flutterViewController.modalPresentationStyle = UIModalPresentationFullScreen;
[self presentViewController:self.flutterViewController animated:YES completion:nil];

2.iOS与flutter通讯
通讯方式共有三种
- BasicMessageChannel通用数据传输，全双工，实时传递
- MethodChannel方法传递通道，传递只执行一次 全双工
- EventChannel事件监听通道持续监听如果电池电量的监听

这里只写MethodChannel写几个方法实现flutter与iOS的方法互调
在iOS中首先要创建消息通道并初始化通道名，这样后面所有消息都通过这个通道名对应的通道传递

//初始化通道
FlutterMethodChannel *methodChannel = [FlutterMethodChannel methodChannelWithName:@"MSGChannel" binaryMessenger:self.flutterViewController.binaryMessenger];
self.methodChannel = methodChannel;

//通过block回调监听通道中来自flutter的消息体 这里做一个dismiss方法，由于iOS中将flutter页面push出来，次数实现dismiss方法，给flutter发送dismss消息，就知道是让iOS将当前页面关闭的动作，iOS收到后，执行关闭操作
__weak typeof(self) weakself = self;
[methodChannel setMethodCallHandler:^(FlutterMethodCall * _Nonnull call, FlutterResult  _Nonnull result) {
    __strong typeof(weakself) strongself = weakself;
    //dissmiss当前页面
    if([call.method isEqualToString:@"dismiss"]){
        [strongself dismissViewControllerAnimated:YES completion:nil];
    }
    if (result) {
        result(@"成功关闭页面");
    }
}];

//iOS中也可以主动给Flutter发消息通过invokeMethod 只需要注意消息通道名要跟初始化保持一致
[self.methodChannel invokeMethod:@"MSGChannel" arguments:@"我是iOS发送过来的消息"];

在flutter中，首先要在main方法中通过window.defaultRouteName的方式获取iOS中传入的Route参数
flutter中同样需要创建消息通道

//创建消息通道并初始化消息名 这个名字要与iOS对应
 static const MethodChannel methodChannel = MethodChannel('MSGChannel');

//设置消息监听
methodChannel.setMethodCallHandler((MethodCall call){
  //接收到消息
  print(call.method);
  print(call.arguments);
  return Future.value(1);
});

//发送消息通过invokeMethod方法
methodChannel.invokeMethod('dismiss');

flutter中完整代码如下

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

void main() => runApp(MyApp(route: window.defaultRouteName));

class MyApp extends StatefulWidget {
  String route;
  MyApp({@required this.route});
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  void initState() {
    super.initState();
    //收到iOS中传入指令
    print(widget.route);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {

//创建消息通道并初始化消息名 这个名字要与iOS对应
 static const MethodChannel methodChannel = MethodChannel('MSGChannel');
 
  @override
  void initState() {
    super.initState();

    //设置消息监听
    methodChannel.setMethodCallHandler((MethodCall call){
      //接收到消息
      print(call.method);
      print(call.arguments);
      return Future.value(true);
    });

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('iOS与Flutter通讯'),
      ),
      body: Center(
        child: GestureDetector(
          onTap: () {
            //发送消息通过invokeMethod方法
             methodChannel.invokeMethod('dismiss');
          },
          child: Container(
            alignment: Alignment.center,
            color: Colors.red,
             100,
            height: 40,
            child: Text(
              '点击返回iOS',
              style: TextStyle(
                color: Colors.white,
              ),
            ),
          ),
        ),
      ),
    );
  }
}

最终效果图如下：

需要特别注意一点：当flutter中内容修改后，需要重新执行sh脚本，将flutter重新打包成framework，在iOS中操作才会有效，要不然改动后，iOS中还是使用的之前的老版本

demo放在github中，如果需要请自取：https://github.com/qqcc1388/flutter_iOS_Mixture

参考来源：

https://juejin.im/post/5e228d21518825265c248e7b
https://blog.csdn.net/qq_28478281/article/details/92416686
https://www.jianshu.com/p/c1034513be13

转载请标注出处https://www.cnblogs.com/qqcc1388/p/12693991.html和参考源 谢谢！