Push Notifications don't appear on devices - ios

Question

I have already written a lot of code in which I set notifications and try to send a notification from a user to another but now here is my problem, there isn't any notification that appears on the other user's device. The app doesn't crash and I have don't have build failed so I really don't know where I am wrong. Thanks in advance for your answers, here's my code...
// Parts about push notifications in AppDelegate.swift
static let NOTIFICATION_URL = "https://gcm-http.googleapis.com/gcm/send"
static var DEVICEID = String()
static let SERVERKEY = "AAAAuIcRiYI:APA91bHA8Q4IJBG9dG4RY9YOZ3v4MlcVZjmYs3XhiMY3xpQm3bTSjrINUiImaE0t17Y6mghR2vN1ezJTMSVFmHlgOUBX8KQZEckgwCkc1tlMdpm_UjxobmrHf3GbvwrKtHVZsJR-v1GG"
#available(iOS 10.0, *){
UNUserNotificationCenter.current().delegate = self
// Request Autorization.
let option : UNAuthorizationOptions = [.alert,.badge,.sound]
UNUserNotificationCenter.current().requestAuthorization(options: option) { (bool, err) in
}
}
else{
let settings : UIUserNotificationSettings = UIUserNotificationSettings(types: [.alert,.badge,.sound], categories: nil)
application.registerUserNotificationSettings(settings)
}
application.registerForRemoteNotifications()
UIApplication.shared.applicationIconBadgeNumber = 0
func messaging(_ messaging: Messaging, didRefreshRegistrationToken fcmToken: String) {
guard let newToken = InstanceID.instanceID().token() else {return}
AppDelegate.DEVICEID = newToken
connectToFCM()
}
func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: #escaping () -> Void) {
let notification = response.notification.request.content.body
print(notification)
completionHandler()
}
func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
guard let token = InstanceID.instanceID().token() else {return}
AppDelegate.DEVICEID = token
print(token)
connectToFCM()
}
func connectToFCM()
{
Messaging.messaging().shouldEstablishDirectChannel = true
}
// Parts about notifications in messages.swift, I call this function after the user sends a message in way that the person who receives the message receives at the same time a notification.
fileprivate func setupPushNotification(fromDevice:String)
{
Database.database().reference().child("users").child(userID).observeSingleEvent(of: .value, with: { (snapshot) in
let value = snapshot.value as? NSDictionary
let device = value?["device"] as? String ?? ""
guard let message = self.authorText else {return}
let title = "You received a new message !"
let body = "from \(message)"
let toDeviceID = device
var headers:HTTPHeaders = HTTPHeaders()
headers = ["Content-Type":"application/json","Authorization":"key=\(AppDelegate.SERVERKEY)"
]
let notification = ["to":"\(toDeviceID)","notification":["body":body,"title":title,"badge":1,"sound":"default"]] as [String:Any]
Alamofire.request(AppDelegate.NOTIFICATION_URL as URLConvertible, method: .post as HTTPMethod, parameters: notification, encoding: JSONEncoding.default, headers: headers).responseJSON { (response) in
print(response)
}
})
}