混合开发模式（Add-to-App）

实现 Flutter 模块嵌入 iOS 原生项目的步骤：

1、在项目根目录用命令创建 Flutter 模块：

例如项目目录这样子

project/
├── ios_project.xcodeproj
├── ios_project.xcworkspace
├── ios_project/
│   ├── AppDelegate.swift
│   └── ...
├── Podfile
├── Podfile.lock
├── flutter_module/
│   ├── lib/
│   ├── .iOS/
│   └── ...

进入到目录

cd project/
flutter create -t module flutter_module

2、将 Flutter 模块集成进 iOS 原生工程

2.1找到pod文件，将Flutter引擎添加到podfile

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

示例:

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



target 'ios_project' do
  use_frameworks!
  install_all_flutter_pods(flutter_application_path)
  
  # 其他你的依赖...
end

post_install do |installer|
  flutter_post_install(installer)
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings["IPHONEOS_DEPLOYMENT_TARGET"] = "12.0"
    end
  end
end

2.2安装 flutter项目依赖、pod安装flutter引擎

cd flutter_module  # 在 Flutter 模块目录下
flutter pub get

cd ..  # 回到 iOS 项目目录
pod install

2.3 iOS项目中添加依赖及初始化引擎

flutter 官方提供了几种方式

2.3.1 提前加载引擎预加载。

import UIKit
import Flutter
import FlutterPluginRegistrant
@main
class AppDelegate: UIResponder, UIApplicationDelegate  {
    lazy var flutterEngine = FlutterEngine(name: "my flutter engine")
    var window: UIWindow?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.rootViewController =   UINavigationController(rootViewController: ViewController())
        window?.makeKeyAndVisible()
        
        flutterEngine.run();
        // Connects plugins with iOS platform code to this app.
        GeneratedPluginRegistrant.register(with: self.flutterEngine);
        return true
    }
}
 
import UIKit
import Flutter
class ViewController: UIViewController {
  override func viewDidLoad() {
    super.viewDidLoad()

    // Make a button to call the showFlutter function when pressed.
    let button = UIButton(type:UIButton.ButtonType.custom)
    button.addTarget(self, action: #selector(showFlutter), for: .touchUpInside)
    button.setTitle("Show Flutter!", for: UIControl.State.normal)
    button.frame = CGRect(x: 80.0, y: 210.0, width: 160.0, height: 40.0)
    button.backgroundColor = UIColor.blue
    self.view.addSubview(button)
  }

  @objc func showFlutter() {
    let flutterEngine = (UIApplication.shared.delegate as! AppDelegate).flutterEngine
    let flutterViewController =
        FlutterViewController(engine: flutterEngine, nibName: nil, bundle: nil)
       present(flutterViewController, animated: true, completion: nil)
    }
  }
}

这种情况适用于提前加载，适用于大量页面，全局引擎，性能好。

用这种方式关闭flutter页面时要注意 引擎持有的vc 置nil 的问题。不然下次打不开了。
可参考下面这种方法：

 ps:   flutter中可用这个调用原生 关闭  下次就无法打开了
         SystemNavigator.pop(animated: true);
当 Flutter 页面通过 SystemNavigator.pop() 关闭时：
Flutter 会直接调用宿主平台的 pop 机制（iOS 上会触发 dismiss）。
但此时 UIKit 并不会 将lutterEngine 持有 的VC 置为 nil

如果你用的 FlutterEngine 是单例的，不会自动 detach，下一次就打不开页面了。
可以这样*/


//
//  File.swift
//  ios_flutter
//
//  Created by liuhao on 2025/5/16.
//

import Foundation
import Flutter

class SafeFlutterViewController: FlutterViewController {

    private var methodChannel: FlutterMethodChannel?

    override func viewDidLoad() {
        super.viewDidLoad()
            methodChannel = FlutterMethodChannel(name: "com.example.flutter/close",
                                                 binaryMessenger: engine.binaryMessenger)
            methodChannel?.setMethodCallHandler { [weak self] call, result in
                if call.method == "popFromFlutter" {
                    self?.dismiss(animated: true) {
                        self?.detachEngineIfNeeded()
                    }
                    result(nil)
                }
         }
    }

    deinit {
        detachEngineIfNeeded()
    }

    private func detachEngineIfNeeded() {
        if  engine.viewController === self {
            engine.viewController = nil
            print("✅ FlutterEngine detached.")
        }
    }
}

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

class NativeNavigator {
  static const _channel = MethodChannel('com.example.flutter/close');

  static Future<void> close() async {
    await _channel.invokeMethod('popFromFlutter');
  }
}
//封装一个专门用于关闭的交互

2.3.2 还可以 每次 新的 engine 。

// Existing code omitted.
func showFlutter() {
  let flutterViewController = FlutterViewController(project: nil, nibName: nil, bundle: nil)
  present(flutterViewController, animated: true, completion: nil)
}
 // flutter中可用这个调用原生 关闭
  // SystemNavigator.pop(animated: true);

作为前一个示例的替代，您可以让其FlutterViewController隐式创建自己的示例，FlutterEngine而无需提前预热。

通常不建议这样做，因为创建FlutterEngine按需加载可能会在呈现和渲染第一帧之间引入明显的延迟FlutterViewController。但是，如果 Flutter 屏幕很少显示，或者没有好的启发式方法来确定何时启动 Dart VM，并且 Flutter 不需要在视图控制器之间持久化状态，那么按需加载可能会很有用。

要让FlutterViewController不存在的现在FlutterEngine，省略构造FlutterEngine，并创建FlutterViewController没有引擎引用的。

3、其他

如遇到错误这个错误

截屏2025-05-08 15.57.24.png

可尝试这样

image.png