How to ask user permission for receiving notifications?

Question

I am using Swift 3.0 and I want the user to be able to click on a button to trigger the alert box that requests his permission for using notifications.

I am surprised not to find more information about that.

I would like to support iOS 9.0 as well as 10.

What is the way to trigger this ask-for-permission alert box again ?

Answer 1

import UserNotifications

and Declare this UNUserNotificationCenterDelegate Method in header

in appDelegates just put this code :

func registerForRemoteNotification() {
        if #available(iOS 10.0, *) {
            let center  = UNUserNotificationCenter.current()

            center.requestAuthorization(options: [.sound, .alert, .badge]) { (granted, error) in
                if error == nil{
                    UIApplication.shared.registerForRemoteNotifications()
                }
            }

        }
        else {
            UIApplication.shared.registerUserNotificationSettings(UIUserNotificationSettings(types: [.sound, .alert, .badge], categories: nil))
            UIApplication.shared.registerForRemoteNotifications()
        }
    }

And when user give permission at that time you can get user token via didRegisterForRemoteNotificationsWithDeviceToken Delegates method

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        let token = deviceToken.map { String(format: "%02.2hhx", $0) }.joined()
        print(token)

        print(deviceToken.description)
        if let uuid = UIDevice.current.identifierForVendor?.uuidString {
            print(uuid)
        }
        UserDefaults.standard.setValue(token, forKey: "ApplicationIdentifier")
        UserDefaults.standard.synchronize()


    }