Flutter与iOS原生混合App二次跳转失败：MissingPluginException问题排查

MissingPluginException 是因为第二次回到Flutter后，MethodChannel的Native端处理逻辑没有和当前Flutter环境绑定。你目前的实现大概率是把通道注册在初始的FlutterViewController生命周期中，当切换到原生页面后，原FlutterViewController被销毁，通道关联失效；再次创建FlutterViewController时，没有重新注册通道处理方法，导致Flutter调用startNativeApp时找不到对应实现。

1. 将MethodChannel注册绑定到全局FlutterEngine #

把通道注册逻辑放在AppDelegate的FlutterEngine初始化阶段，确保全局唯一的FlutterEngine始终持有通道处理逻辑，不管创建多少个FlutterViewController，通道都能正常响应。

修改AppDelegate代码：

import Flutter

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    // 全局持久化的Flutter引擎
    let flutterEngine = FlutterEngine(name: "persistent_flutter_engine")

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // 预启动Flutter引擎，避免冷启动延迟
        flutterEngine.run()
        
        // 注册MethodChannel并绑定处理逻辑
        let nativeChannel = FlutterMethodChannel(name: "nativeChannel", binaryMessenger: flutterEngine.binaryMessenger)
        nativeChannel.setMethodCallHandler { [weak self] call, result in
            switch call.method {
            case "startNativeApp":
                // 执行原生页面跳转
                self?.presentLauncherViewController()
                result.success(nil)
            default:
                result.notImplemented()
            }
        }
        
        return true
    }

    // 你的原生页面跳转方法
    func presentLauncherViewController() {
        if let launcherViewController = LaunchVC.instantiateFromStoryboard() {
            launcherViewController.modalPresentationStyle = .fullScreen
            if let window = self.window {
                window.rootViewController = launcherViewController as! UINavigationController
                window.makeKeyAndVisible()
            }
        }
    }
}

2. 跳转到Flutter时复用全局引擎 #

保持你原有的跳转代码不变即可，因为已经在使用AppDelegate中的全局flutterEngine创建FlutterViewController，新的ViewController会复用已注册通道的引擎：

let appDelegate = UIApplication.shared.delegate as! AppDelegate
let flutterEngine = appDelegate.flutterEngine
let flutterViewController = FlutterViewController(engine: flutterEngine, nibName: nil, bundle: nil)

flutterViewController.modalPresentationStyle = .fullScreen
if let window = appDelegate.window {
    window.rootViewController = flutterViewController
    window.makeKeyAndVisible()
}

3. 禁止重复创建FlutterEngine #

不要每次跳转Flutter都新建引擎，复用全局的flutterEngine，既能保持通道有效性，还能提升Flutter页面的启动速度。

1. 应用启动进入Flutter页面，此时全局引擎已注册通道，调用startNativeApp可正常跳转原生页面。
2. 从原生跳转回Flutter时，复用全局引擎创建ViewController，通道依然有效，Flutter再次调用startNativeApp时，Native端能正常响应并执行跳转。

内容的提问来源于stack exchange，提问作者Devenom