iOS Registering for (Non Interactive) Push Notification


Example

The logic of registering for push notification is recommended to be added in AppDelegate.swift as the callback functions (success, failure) will be called their. To register just do the following:

let application = UIApplication.sharedApplication()
let settings = UIUserNotificationSettings(forTypes: [.Alert, .Badge, .Sound], categories: nil)
application.registerUserNotificationSettings(settings)

Then the callback function didRegisterUserNotificationSettings will be called and in that case you just trigger the register like this:

func application(application: UIApplication, didRegisterUserNotificationSettings notificationSettings: UIUserNotificationSettings) {
    application.registerForRemoteNotifications()
}

And in that case and system alert will be shown asking for persmission to receive push notification. One of the following callback functions will be called:

func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
    let tokenChars = UnsafePointer<CChar>(deviceToken.bytes)
    var tokenString = ""
    
    for i in 0..<deviceToken.length {
        tokenString += String(format: "%02.2hhx", arguments: [tokenChars[i]])
    }
    
    print("Push token: \(tokenString)")
}

func application(application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: NSError) {
    print("didFailToRegisterForRemoteNotificationsWithError: \(error)")
            
}

In very rare cases, neither success or failure callback functions are called. This happens when you have internet connection problems or the APNS Sandbox is down. The system do an API call to APNS to do some verification, failing to do so will lead to none of the two callbacks functions will be called. Visit Apple system status to make sure its fine.