PushNotifications not working properly(reliably) in iOS - ios

Question

I am facing some issues with push notifications. We are using Firebase for Push Notificaions. The thing is I am able to receive PushNotifications properly on one iPhone but can’t get them on another iPhone. And I am getting Notifications properly on Android.
What I am doing is Signing-In from a same account and trying push notifications. What is happening is am getting on all android phones, on my iPhone 5S most of all but very few on my iPhone 6.
Here is the code which is used in AppDelegate for setting up the connection.
func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
InstanceID.instanceID().setAPNSToken(deviceToken, type: InstanceIDAPNSTokenType.sandbox)
}
#objc func tokenRefreshNotification(notification: Notification){
print("entered tokenRefreshNotification")
let refreshedToken = InstanceID.instanceID().token()
if refreshedToken != nil{
UserDefaults.standard.setValue(refreshedToken, forKey: "token")
}
//UserDefaults.standard.setValue(refreshedToken, forKey: "token")
print("Instance ID token: \(String(describing: refreshedToken))")
connectToFCM()
}
func connectToFCM(){
Messaging.messaging().connect { (error) in
if error != nil{
self.print("Unable to connect to FCM \(String(describing: error))")
return
}
self.print("connected to FCM")
}
}
func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any]) {
print("application did receive remote notification")
print(userInfo)
let notification = UILocalNotification()
notification.fireDate = Date()
let notificationType = (userInfo["type"] as! String).lowercased()
switch notificationType {
case "alert" :
print("Show notifications and save in the notifications list.")
notification.alertBody = userInfo["message"] as? String
//code for saving to user defaults
if var notifications = userDefaults.value(forKey: keys.notificationsList) as? [String] {
if let notificationString = notification.alertBody{
notifications.append(notificationString)
userDefaults.setValue(notifications, forKey: keys.notificationsList)
}
} else{
//in case of empty notificationList
if let notificationString = notification.alertBody{
let notifications = [notificationString]
userDefaults.setValue(notifications, forKey: keys.notificationsList)
}
}
//notifications.append(notification.alertBody)
UIApplication.shared.scheduleLocalNotification(notification)
case "advertisement" :
print("Just show the notification and do nothing else.")
notification.alertBody = userInfo["message"] as? String
UIApplication.shared.scheduleLocalNotification(notification)
case "cleardb":
print("Clear everything from Database, but not logout user.")
notification.alertBody = "All data from database had been wiped"
UIApplication.shared.scheduleLocalNotification(notification)
case "update_device":
print("device_data has been updated so download devices info again")
case "logout":
print("logout the user")
Functions.functions.wipeUserDefaults()
notification.alertBody = "Logged out of Ryoking"
UIApplication.shared.scheduleLocalNotification(notification)
default:
print("lol")
}
}
func application(received remoteMessage: MessagingRemoteMessage) {
print("application received remote message")
print(remoteMessage.appData)
}

Answer 1

I have followed this steps from firebase console literally and it works for me like a charm, try it out:
https://firebase.google.com/docs/cloud-messaging/ios/first-message?authuser=0