在Swift 4中将UNNotificationAction添加到firebase FCM推送通知

在Swift 4中，将UNNotificationAction添加到Firebase FCM推送通知是通过以下步骤实现的：

首先，确保你已经集成了Firebase SDK到你的Swift项目中，并且已经设置了Firebase Cloud Messaging（FCM）。
在AppDelegate.swift文件中，导入UserNotifications和FirebaseMessaging框架：

import UserNotifications
import FirebaseMessaging

在AppDelegate类中，添加UNUserNotificationCenterDelegate协议，并在didFinishLaunchingWithOptions方法中注册远程通知：

class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        
        // 注册远程通知
        UNUserNotificationCenter.current().delegate = self
        UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { (granted, error) in
            if granted {
                DispatchQueue.main.async {
                    application.registerForRemoteNotifications()
                }
            }
        }
        
        // Firebase配置
        FirebaseApp.configure()
        
        return true
    }
    
    // 远程通知注册成功
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        Messaging.messaging().apnsToken = deviceToken
    }
    
    // 远程通知注册失败
    func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
        print("Failed to register for remote notifications: \(error.localizedDescription)")
    }
    
    // 接收到远程通知
    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any]) {
        // 处理通知内容
    }
    
    // iOS 10以上版本接收到远程通知
    @available(iOS 10.0, *)
    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
        // 处理通知点击事件
    }
}

在AppDelegate类中，实现UNUserNotificationCenterDelegate协议的方法，以处理通知的显示和点击事件：

extension AppDelegate {
    
    // iOS 10以上版本显示通知
    @available(iOS 10.0, *)
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        // 处理通知显示
    }
    
    // iOS 10以上版本点击通知
    @available(iOS 10.0, *)
    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
        // 处理通知点击事件
        if response.actionIdentifier == UNNotificationDefaultActionIdentifier {
            // 默认点击事件
        } else if response.actionIdentifier == "ActionIdentifier" {
            // 自定义点击事件
        }
        
        completionHandler()
    }
}

在发送FCM推送通知时，需要在通知的payload中添加自定义的action字段，用于标识点击通知时的行为。例如：

{
  "to": "device_token",
  "notification": {
    "title": "Notification Title",
    "body": "Notification Body"
  },
  "data": {
    "action": "ActionIdentifier"
  }
}