【Flutter 混合开发】嵌入原生View-iOS

时间  2020-10-20
标签 android ios git 微信 app less async ide 函数 栏目 iOS 繁體版
原文   原文链接

Flutter 混合开发系列 包含以下：android

  • 嵌入原生View-Android
  • 嵌入原生View-iOS
  • 与原生通讯-MethodChannel
  • 与原生通讯-BasicMessageChannel
  • 与原生通讯-EventChannel
  • 添加 Flutter 到 Android Activity
  • 添加 Flutter 到 Android Fragment
  • 添加 Flutter 到 iOS

每一个工做日分享一篇，欢迎关注、点赞及转发。ios

iOS View

建议使用 Xcode 进行开发，在 Android Studio 左侧 project tab下选中 ios 目录下任意一个文件，右上角会出现 Open iOS module in Xcode ，git

点击便可打开，打开后以下：微信

在Runner 目录下建立 iOS View，此 View 继承 FlutterPlatformView ，返回一个简单的 UILabel ：app

import Foundation
import Flutter

class MyFlutterView: NSObject,FlutterPlatformView {
    
    let label = UILabel()
    
    init(_ frame: CGRect,viewID: Int64,args :Any?,messenger :FlutterBinaryMessenger) {
        label.text = "我是 iOS View"
    }
    
    func view() -> UIView {
        return label
    }   
}
  • getView ：返回iOS View

注册PlatformView

建立 MyFlutterViewFactory：less

import Foundation
import Flutter

class MyFlutterViewFactory: NSObject,FlutterPlatformViewFactory {
    
    var messenger:FlutterBinaryMessenger
    
    init(messenger:FlutterBinaryMessenger) {
        self.messenger = messenger
        super.init()
    }
    
    func create(withFrame frame: CGRect, viewIdentifier viewId: Int64, arguments args: Any?) -> FlutterPlatformView {
        return MyFlutterView(frame,viewID: viewId,args: args,messenger: messenger)
    }
    
    func createArgsCodec() -> FlutterMessageCodec & NSObjectProtocol {
        return FlutterStandardMessageCodec.sharedInstance()
    }
}

在 AppDelegate 中注册：async

import UIKit
import Flutter

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)
    
    let registrar:FlutterPluginRegistrar = self.registrar(forPlugin: "plugins.flutter.io/custom_platform_view_plugin")!
    let factory = MyFlutterViewFactory(messenger: registrar.messenger())
    registrar.register(factory, withId: "plugins.flutter.io/custom_platform_view")
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

记住 plugins.flutter.io/custom_platform_view ，这个字符串在 Flutter 中须要与其保持一致。ide

嵌入Flutter

在 Flutter 中调用函数

class PlatformViewDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    Widget platformView() {
      if (defaultTargetPlatform == TargetPlatform.android) {
        return AndroidView(
          viewType: 'plugins.flutter.io/custom_platform_view',
          onPlatformViewCreated: (viewId) {
            print('viewId:$viewId');
            platforms
                .add(MethodChannel('com.flutter.guide.MyFlutterView_$viewId'));
          },
          creationParams: {'text': 'Flutter传给AndroidTextView的参数'},
          creationParamsCodec: StandardMessageCodec(),
        );
      }else if(defaultTargetPlatform == TargetPlatform.iOS){
        return UiKitView(
          viewType: 'plugins.flutter.io/custom_platform_view',
        );
      }
    }
    return Scaffold(
      appBar: AppBar(),
      body: Center(
        child: platformView(),
      ),
    );
  }
}

上面嵌入的是 iOS View，所以经过 defaultTargetPlatform == TargetPlatform.iOS 判断当前平台加载，在 iOS 上运行效果：ui

设置初始化参数

Flutter 端修改以下：

UiKitView(
          viewType: 'plugins.flutter.io/custom_platform_view',
          creationParams: {'text': 'Flutter传给IOSTextView的参数'},
          creationParamsCodec: StandardMessageCodec(),
        )
  • creationParams ：传递的参数，插件能够将此参数传递给 AndroidView 的构造函数。
  • creationParamsCodec ：将 creationParams 编码后再发送给平台侧，它应该与传递给构造函数的编解码器匹配。值的范围：
    • StandardMessageCodec
    • JSONMessageCodec
    • StringCodec
    • BinaryCodec

修改 MyFlutterView ：

import Foundation
import Flutter

class MyFlutterView: NSObject,FlutterPlatformView {
    
    let label = UILabel()
    
    init(_ frame: CGRect,viewID: Int64,args :Any?,messenger :FlutterBinaryMessenger) {
        super.init()
        if(args is NSDictionary){
            let dict = args as! NSDictionary
            label.text  = dict.value(forKey: "text") as! String
        }
    }
    
    func view() -> UIView {
        return label
    }
    
}

最终效果：

Flutter 向 iOS View 发送消息

修改 Flutter 端，建立 MethodChannel 用于通讯：

class PlatformViewDemo extends StatefulWidget {
  @override
  _PlatformViewDemoState createState() => _PlatformViewDemoState();
}

class _PlatformViewDemoState extends State<PlatformViewDemo> {
  static const platform =
      const MethodChannel('com.flutter.guide.MyFlutterView');

  @override
  Widget build(BuildContext context) {
		Widget platformView() {
      if (defaultTargetPlatform == TargetPlatform.android) {
        return AndroidView(
          viewType: 'plugins.flutter.io/custom_platform_view',
          creationParams: {'text': 'Flutter传给AndroidTextView的参数'},
          creationParamsCodec: StandardMessageCodec(),
        );
      } else if (defaultTargetPlatform == TargetPlatform.iOS) {
        return UiKitView(
          viewType: 'plugins.flutter.io/custom_platform_view',
          creationParams: {'text': 'Flutter传给IOSTextView的参数'},
          creationParamsCodec: StandardMessageCodec(),
        );
      }
    }

    return Scaffold(
      appBar: AppBar(),
      body: Column(children: [
        RaisedButton(
          child: Text('传递参数给原生View'),
          onPressed: () {
            platform.invokeMethod('setText', {'name': 'laomeng', 'age': 18});
          },
        ),
        Expanded(child: platformView()),
      ]),
    );
  }
}

在 原生View 中也建立一个 MethodChannel 用于通讯：

import Foundation
import Flutter

class MyFlutterView: NSObject,FlutterPlatformView {
    
    let label = UILabel()
    
    init(_ frame: CGRect,viewID: Int64,args :Any?,messenger :FlutterBinaryMessenger) {
        super.init()
        if(args is NSDictionary){
            let dict = args as! NSDictionary
            label.text  = dict.value(forKey: "text") as! String
        }
        
        let methodChannel = FlutterMethodChannel(name: "com.flutter.guide.MyFlutterView", binaryMessenger: messenger)
        methodChannel.setMethodCallHandler { (call, result) in
            if (call.method == "setText") {
                if let dict = call.arguments as? Dictionary<String, Any> {
                    let name:String = dict["name"] as? String ?? ""
                    let age:Int = dict["age"] as? Int ?? -1
                    self.label.text = "hello,\(name),年龄：\(age)"
                }
            }
        }
    }
    
    func view() -> UIView {
        return label
    }
    
}

Flutter 向 Android View 获取消息

与上面发送信息不一样的是，Flutter 向原生请求数据，原生返回数据到 Flutter 端，修改 MyFlutterView onMethodCall：

import Foundation
import Flutter

class MyFlutterView: NSObject,FlutterPlatformView {
    
    let label = UILabel()
    
    init(_ frame: CGRect,viewID: Int64,args :Any?,messenger :FlutterBinaryMessenger) {
        super.init()
        if(args is NSDictionary){
            let dict = args as! NSDictionary
            label.text  = dict.value(forKey: "text") as! String
        }
        
        let methodChannel = FlutterMethodChannel(name: "com.flutter.guide.MyFlutterView", binaryMessenger: messenger)
        methodChannel.setMethodCallHandler { (call, result:FlutterResult) in
            if (call.method == "setText") {
                if let dict = call.arguments as? Dictionary<String, Any> {
                    let name:String = dict["name"] as? String ?? ""
                    let age:Int = dict["age"] as? Int ?? -1
                    self.label.text = "hello,\(name),年龄：\(age)"
                }
            }else if (call.method == "getData") {
                if let dict = call.arguments as? Dictionary<String, Any> {
                    let name:String = dict["name"] as? String ?? ""
                    let age:Int = dict["age"] as? Int ?? -1
                    result(["name":name,"age":age])
                }
            }
        }
    }
    
    func view() -> UIView {
        return label
    }
    
}

result() 是返回的数据。

Flutter 端接收数据：

var _data = '获取数据';

RaisedButton(
  child: Text('$_data'),
  onPressed: () async {
    var result = await platform
        .invokeMethod('getData', {'name': 'laomeng', 'age': 18});
    setState(() {
      _data = '${result['name']},${result['age']}';
    });
  },
),

解决多个原生View通讯冲突问题

固然页面有3个原生View，

class PlatformViewDemo extends StatefulWidget {
  @override
  _PlatformViewDemoState createState() => _PlatformViewDemoState();
}

class _PlatformViewDemoState extends State<PlatformViewDemo> {
  static const platform =
      const MethodChannel('com.flutter.guide.MyFlutterView');

  var _data = '获取数据';

  @override
  Widget build(BuildContext context) {
		Widget platformView() {
      if (defaultTargetPlatform == TargetPlatform.android) {
        return AndroidView(
          viewType: 'plugins.flutter.io/custom_platform_view',
          creationParams: {'text': 'Flutter传给AndroidTextView的参数'},
          creationParamsCodec: StandardMessageCodec(),
        );
      } else if (defaultTargetPlatform == TargetPlatform.iOS) {
        return UiKitView(
          viewType: 'plugins.flutter.io/custom_platform_view',
          creationParams: {'text': 'Flutter传给IOSTextView的参数'},
          creationParamsCodec: StandardMessageCodec(),
        );
      }
    }

    return Scaffold(
      appBar: AppBar(),
      body: Column(children: [
        Row(
          children: [
            RaisedButton(
              child: Text('传递参数给原生View'),
              onPressed: () {
                platform
                    .invokeMethod('setText', {'name': 'laomeng', 'age': 18});
              },
            ),
            RaisedButton(
              child: Text('$_data'),
              onPressed: () async {
                var result = await platform
                    .invokeMethod('getData', {'name': 'laomeng', 'age': 18});
                setState(() {
                  _data = '${result['name']},${result['age']}';
                });
              },
            ),
          ],
        ),
        Expanded(child: Container(color: Colors.red, child: platformView())),
        Expanded(child: Container(color: Colors.blue, child: platformView())),
        Expanded(child: Container(color: Colors.yellow, child: platformView())),
      ]),
    );
  }
}

此时点击 传递参数给原生View 按钮哪一个View会改变内容，实际上只有最后一个会改变。

如何改变指定View的内容？重点是 MethodChannel，只需修改上面3个通道的名称不相同便可：

  • 第一种方法：将一个惟一 id 经过初始化参数传递给原生 View，原生 View使用这个id 构建不一样名称的 MethodChannel。
  • 第二种方法（推荐）：原生 View 生成时，系统会为其生成惟一id：viewId，使用 viewId 构建不一样名称的 MethodChannel。

原生 View 使用 viewId 构建不一样名称的 MethodChannel：

import Foundation
import Flutter

class MyFlutterView: NSObject,FlutterPlatformView {
    
    let label = UILabel()
    
    init(_ frame: CGRect,viewID: Int64,args :Any?,messenger :FlutterBinaryMessenger) {
        super.init()
        if(args is NSDictionary){
            let dict = args as! NSDictionary
            label.text  = dict.value(forKey: "text") as! String
        }
        
        let methodChannel = FlutterMethodChannel(name: "com.flutter.guide.MyFlutterView_\(viewID)", binaryMessenger: messenger)
        methodChannel.setMethodCallHandler { (call, result:FlutterResult) in
            ...
        }
    }
    
    func view() -> UIView {
        return label
    }
    
}

Flutter 端为每个原生 View 建立不一样的MethodChannel：

var platforms = [];

UiKitView(
  viewType: 'plugins.flutter.io/custom_platform_view',
  onPlatformViewCreated: (viewId) {
    print('viewId:$viewId');
    platforms
        .add(MethodChannel('com.flutter.guide.MyFlutterView_$viewId'));
  },
  creationParams: {'text': 'Flutter传给AndroidTextView的参数'},
  creationParamsCodec: StandardMessageCodec(),
)

给第一个发送消息：

platforms[0]
    .invokeMethod('setText', {'name': 'laomeng', 'age': 18});

交流

老孟Flutter博客（330个控件用法+实战入门系列文章）：http://laomengit.com

欢迎加入Flutter交流群（微信：laomengit）、关注公众号【老孟Flutter】：
相关文章
相关标签/搜索
每日一句
    每一个你不满意的现在，都有一个你没有努力的曾经。
本站公众号
   欢迎关注本站公众号,获取更多信息
联系我们 最近搜索 最新文章 沪ICP备13005482号-10 MyBatis教程 SQL 教程 MySQL教程 Java 教程 Thymeleaf 教程 Hibernate教程 Spring教程 Redis教程