React Native 0.66.4升级至0.69.6：保留AppDelegate.swift逻辑方案

核心结论 #

完全不需要把Swift代码硬整合到AppDelegate.mm里，最优方案是让Swift版AppDelegate继续承载业务逻辑，通过Objective-C桥接，用.mm文件作为RN要求的入口层转发调用，既满足RN 0.69+对.mm文件的要求，又能100%复用原有Swift代码。

具体实现步骤 #

1. 保留原有Swift代码：不要修改你的AppDelegate.swift，所有业务逻辑（比如推送配置、RN初始化、第三方SDK集成等）继续留在这个文件里。
2. 确保桥接配置正常：如果项目之前没有桥接文件，需要在Xcode的Build Settings里设置Objective-C Bridging Header，指向你的桥接文件（比如YourProject-Bridging-Header.h）；如果已经有，确认它能正常导入Swift需要的Objective-C依赖。
3. 创建AppDelegate.mm作为入口：这个文件只做转发，把UIApplication的生命周期事件传递给Swift版的AppDelegate实例。

示例代码 #

原有AppDelegate.swift（保留逻辑） #

import UIKit
import React

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    var bridge: RCTBridge?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // 原有RN初始化逻辑
        let jsCodeLocation: URL
        #if DEBUG
        jsCodeLocation = RCTBundleURLProvider.sharedSettings().jsBundleURL(forBundleRoot: "index")
        #else
        jsCodeLocation = Bundle.main.url(forResource: "main", withExtension: "jsbundle")!
        #endif

        bridge = RCTBridge(delegate: self, launchOptions: launchOptions)
        let rootView = RCTRootView(bridge: bridge!, moduleName: "YourAppName", initialProperties: nil)
        
        window = UIWindow(frame: UIScreen.main.bounds)
        let rootViewController = UIViewController()
        rootViewController.view = rootView
        window?.rootViewController = rootViewController
        window?.makeKeyAndVisible()
        
        // 原有其他逻辑：比如推送注册、第三方SDK初始化等
        registerPushNotifications()
        
        return true
    }

    // 其他生命周期方法，比如推送回调、RN模块注册等
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        // 原有处理逻辑
    }
}

extension AppDelegate: RCTBridgeDelegate {
    func sourceURL(for bridge: RCTBridge!) -> URL! {
        #if DEBUG
        return RCTBundleURLProvider.sharedSettings().jsBundleURL(forBundleRoot: "index")
        #else
        return Bundle.main.url(forResource: "main", withExtension: "jsbundle")
        #endif
    }
}

private extension AppDelegate {
    func registerPushNotifications() {
        // 原有推送注册逻辑
        UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound]) { granted, error in
            if granted {
                DispatchQueue.main.async {
                    UIApplication.shared.registerForRemoteNotifications()
                }
            }
        }
    }
}

新创建的AppDelegate.mm（仅做转发） #

#import <UIKit/UIKit.h>
// 导入Swift自动生成的头文件，注意替换成你的项目名称
#import "YourProjectName-Swift.h"

@interface AppDelegate () <UIApplicationDelegate>
@property (nonatomic, strong) AppDelegate *swiftDelegate;
@end

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.swiftDelegate = [[AppDelegate alloc] init];
    return [self.swiftDelegate application:application didFinishLaunchingWithOptions:launchOptions];
}

// 转发所有需要的生命周期方法到SwiftDelegate
- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
    [self.swiftDelegate application:application didRegisterForRemoteNotificationsWithDeviceToken:deviceToken];
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
    [self.swiftDelegate application:application didReceiveRemoteNotification:userInfo fetchCompletionHandler:completionHandler];
}

// 其他需要的生命周期方法，比如applicationWillResignActive、applicationDidBecomeActive等，按需添加
- (void)applicationWillResignActive:(UIApplication *)application {
    [self.swiftDelegate applicationWillResignActive:application];
}

@end

注意事项 #

• 替换示例中的YourProjectName为你的实际项目名称，Swift自动生成的头文件格式是项目名-Swift.h
• 如果Swift版AppDelegate里有自定义方法，需要在Swift代码前加上@objc修饰，才能在.mm文件中调用
• 确保Xcode的Build Settings里，Objective-C Generated Interface Header Name设置正确（默认就是项目名-Swift.h）

内容的提问来源于stack exchange，提问作者Solly