如何在Xamarin.iOS（C#）中基于Firebase实现FCM推送通知？

Hey there, I’ve been right where you are—struggling to get FCM push notifications working in a Xamarin.iOS app with Firebase backend. Let me share a complete, tested AppDelegate.cs implementation that should get you up and running, plus key tips to avoid common pitfalls.

Full AppDelegate.cs Code #

using Foundation;
using UIKit;
using Firebase.Core;
using Firebase.Messaging;

namespace YourAppNamespace
{
    [Register("AppDelegate")]
    public class AppDelegate : UIApplicationDelegate, IUNUserNotificationCenterDelegate, IMessagingDelegate
    {
        public override UIWindow Window { get; set; }

        public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
        {
            // 初始化 Firebase 核心服务
            Firebase.Core.App.Configure();

            // 配置用户通知中心并请求权限
            UNUserNotificationCenter.Current.Delegate = this;
            var authOptions = UNAuthorizationOptions.Alert | UNAuthorizationOptions.Badge | UNAuthorizationOptions.Sound;
            UNUserNotificationCenter.Current.RequestAuthorization(authOptions, (granted, error) =>
            {
                if (granted)
                {
                    // 在主线程注册远程通知
                    InvokeOnMainThread(() => UIApplication.SharedApplication.RegisterForRemoteNotifications());
                }
            });

            // 设置 FCM Messaging 的代理
            Messaging.SharedInstance.Delegate = this;

            // 处理从推送通知启动应用的情况（可选）
            if (launchOptions != null)
            {
                var remoteNotification = launchOptions[UIApplication.LaunchOptionsRemoteNotificationKey] as NSDictionary;
                if (remoteNotification != null)
                {
                    HandleNotificationContent(remoteNotification);
                }
            }

            return true;
        }

        // 成功获取 APNs 设备令牌后，同步到 FCM
        public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
        {
            // 转换令牌格式：去掉尖括号和空格，适配 FCM 要求
            var fcmToken = deviceToken.Description.Trim('<', '>').Replace(" ", "");
            Messaging.SharedInstance.ApnsToken = deviceToken;
            
            // 这里可以将令牌发送到你的后端服务器保存，用于定向推送
            System.Console.WriteLine($"FCM Device Token: {fcmToken}");
        }

        // 注册远程通知失败的回调
        public override void FailedToRegisterForRemoteNotifications(UIApplication application, NSError error)
        {
            System.Console.WriteLine($"Failed to register for remote notifications: {error.LocalizedDescription}");
        }

        // 应用在前台时接收通知的处理（控制是否显示横幅/声音/角标）
        [Export("userNotificationCenter:willPresentNotification:withCompletionHandler:")]
        public void WillPresentNotification(UNUserNotificationCenter center, UNNotification notification, System.Action<UNNotificationPresentationOptions> completionHandler)
        {
            // 解析并处理通知内容
            HandleNotificationContent(notification.Request.Content.UserInfo);
            
            // 设置前台显示通知的方式：同时显示横幅、播放声音、更新角标
            completionHandler(UNNotificationPresentationOptions.Alert | UNNotificationPresentationOptions.Sound | UNNotificationPresentationOptions.Badge);
        }

        // 用户点击通知后的处理逻辑
        [Export("userNotificationCenter:didReceiveNotificationResponse:withCompletionHandler:")]
        public void DidReceiveNotificationResponse(UNUserNotificationCenter center, UNNotificationResponse response, System.Action completionHandler)
        {
            // 解析并处理通知内容
            HandleNotificationContent(response.Notification.Request.Content.UserInfo);
            
            // 必须调用完成回调
            completionHandler();
        }

        // 接收 FCM 数据消息的回调（即使应用在后台或终止状态）
        public void DidReceiveMessage(Messaging messaging, RemoteMessage remoteMessage)
        {
            System.Console.WriteLine($"Received FCM Data Message: {remoteMessage.AppData}");
            // 处理数据消息内容
            HandleNotificationContent(remoteMessage.AppData);
        }

        // 统一处理通知内容的私有方法
        private void HandleNotificationContent(NSDictionary notificationData)
        {
            // 根据你的通知结构解析字段，这里是示例解析 title 和 body
            if (notificationData.TryGetValue(new NSString("title"), out NSObject titleObj) && 
                notificationData.TryGetValue(new NSString("body"), out NSObject bodyObj))
            {
                var title = titleObj.ToString();
                var body = bodyObj.ToString();
                System.Console.WriteLine($"Notification Received - Title: {title}, Body: {body}");
                
                // 这里可以添加自定义逻辑：比如弹出弹窗、导航到指定页面等
            }
        }
    }
}

Critical Setup Notes #

Don’t forget these steps—they’re the most common reasons FCM fails in Xamarin.iOS:

• Firebase Config File: Add GoogleService-Info.plist to your project, set its Build Action to BundleResource (right-click the file in Solution Explorer -> Properties).
• Required NuGet Packages: Install these via NuGet Package Manager:
  • Xamarin.Firebase.iOS.Core
  • Xamarin.Firebase.iOS.Messaging
  • Xamarin.iOS.UserNotifications (usually installed automatically, but double-check)
• Apple Developer Portal Setup:
  • Enable Push Notifications for your app ID.
  • Generate and upload both Development and Production APNs certificates to the Firebase Console (Project Settings -> Cloud Messaging).
• Background Modes: Enable Remote notifications in your project’s Info.plist (Visual Studio: Project Properties -> iOS Application -> Background Modes -> Check "Remote notifications").
• iOS Version Target: Make sure your deployment target is at least iOS 10.0—UNUserNotificationCenter doesn’t work on older versions.

内容的提问来源于stack exchange，提问作者mahmudamen