Flutter进阶-混合开发上篇

Flutter调用原生

咱们用之前的微信Demo的个人中心头像来做示例，点击头像的时分，唤醒原生的相册。

GestureDetector(
  onTap: () {
     print('需求引发原生的 相机');
    _methodChannel.invokeMapMethod('takePhotos');
  },
  child: Container(
     width: 70,
     height: 70,
     decoration: BoxDecoration(
        image:
          DecorationImage(image: AssetImage('images/游戏2.png')),
             borderRadius: BorderRadius.circular(10)),
  ),
),

在Flutter和 iOS中通讯供给了一个专门的类MethodChannel用来通信

 MethodChannel _methodChannel = MethodChannel('mine/method');

在onTap的时分调用_methodChannel.invokeMapMethod('takePhotos');告诉iOS原生我向你发起了一个takePhotos的办法，iOS你在接收到这个标识的时分要给我调起你自己的相机哦~ ​

此刻咱们来到iOS的项目中：

1. 首要示例化FlutterMethodChannel这个类，该类的第一个参数是指明哪个途径下的办法
2. 调用setMethodCallHandler来呼应Flutter发出来的讯息
3. 辨认当时的办法针对处理

import UIKit
import Flutter
@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
    var pickVc = UIImagePickerController()
    var flutterChannel: FlutterMethodChannel!
    override func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        GeneratedPluginRegistrant.register(with: self)
        let vc = self.window.rootViewController as? FlutterViewController
        pickVc.delegate = self
      	// 在iOS端也初始话这个通讯的类
        flutterChannel = FlutterMethodChannel.init(name: "mine/method", binaryMessenger: vc as! FlutterBinaryMessenger)
      	// 对Flutter端发过来的通讯处理
        flutterChannel.setMethodCallHandler { call, result in
            // 如果我辨认了这个办法是`takePhotos`  我就引发原生相机                               
            if call.method.isEqual("takePhotos"){
                print("办法来了");
                self.pickVc.delegate = self
                vc?.present(self.pickVc, animated: true, completion: nil)
            }
        }
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
}

4. 当然啦，在iOS中选中了照片，把照片中的信息再回传给Flutter中，调用invokeMethod回传

extension AppDelegate: UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        if let imagePathURL = info[UIImagePickerController.InfoKey.imageURL] as? NSURL,
           let imagePath = imagePathURL.absoluteString {
            self.flutterChannel.invokeMethod("editedImage", arguments: imagePath)
        }
        picker.dismiss(animated: true, completion: nil)   
    }
    func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
        picker.dismiss(animated: true, completion: nil)
    } 
}

5.Flutter中收到iOS原生端挑选的图片之后，也呼应setMethodCallHandler

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    _methodChannel.setMethodCallHandler((call) {
      if (call.method == 'editedImage') {
        print(call.arguments);
      }
      return call.arguments;
    });
  }

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    _methodChannel.setMethodCallHandler((call) {
      if (call.method == 'editedImage') {
        print(call.arguments);
        setState(() {
          String subString = call.arguments.toString().substring(7);
          _avatarFile = File(subString);
        });
      }
      return call.arguments;
    });
  }
BoxDecoration(
   image: DecorationImage(
            image: _avatarFile == null
             ? AssetImage('images/游戏2.png') as ImageProvider
             : FileImage(_avatarFile!),
             fit: BoxFit.cover),
   borderRadius: BorderRadius.circular(10)
)

image_picker

还有一种运用pub的方法唤醒相机，这儿运用到了Flutter官方出品的一个库image_picker

咱们安装之后能够参考一下用法，本文的运用还是比较简单的

  void _pickerImage() async {
    try {
      XFile? file = await _picker.pickImage(source: ImageSource.gallery);
      if (file != null && mounted) {
        setState(() {
          _avatarFile = File(file.path);
        });
      }
    } catch (e) {
      print(e.toString());
      setState(() {
        _avatarFile = null;
      });
    }
  }

其间这儿有一个小bug，当咱们挑选模拟器中的第一个相片的时分；会报错，所以在此刻加了 异常处理

温馨提示：记得要在iOS的info.plist文件中装备相册的权限！