如何控制何时在iOS中提示用户推送通知权限

Question

I've built an application for iPhone using Swift and Xcode 6, and the Parse framework to handle services.

While following the Parse tutorials on how to set up push notifications, the instructions advised that I put the push notifications in the App Delegate file.

This is the code that I have added to the App Delegate file...

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    var pushNotificationsController: PushNotificationController?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

         // Register for Push Notifications
        self.pushNotificationsController = PushNotificationController()

        if application.respondsToSelector("registerUserNotificationSettings:") {
            println("registerUserNotificationSettings.RegisterForRemoteNotificatios")
            let userNotificationTypes: UIUserNotificationType = (.Alert | .Badge | .Sound)
            let settings:UIUserNotificationSettings = UIUserNotificationSettings(forTypes: userNotificationTypes, categories: nil)
            application.registerUserNotificationSettings(settings)
            application.registerForRemoteNotifications()
        }

        return true;
    }

    func application(application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
        println("didRegisterForRemoteNotificationsWithDeviceToken")
        let installation = PFInstallation.currentInstallation()
        installation.setDeviceTokenFromData(deviceToken)
        installation.saveInBackground()
    }
}

So what happens is that as soon as the application is launched for the first time, the user is prompted to grant these permissions.

What I want to do, is only prompt for these permissions after a certain action has taken place (ie, during a walkthrough of the features of the app) so I can provide a little more context on why we would want them to allow push notifications.

Is it as simple as just copying the below code in the relevant ViewController where I will be expecting to prompt the user?

// In 'MainViewController.swift' file

func promptUserToRegisterPushNotifications() {
        // Register for Push Notifications
        self.pushNotificationsController = PushNotificationController()

        if application.respondsToSelector("registerUserNotificationSettings:") {
            println("registerUserNotificationSettings.RegisterForRemoteNotificatios")
            let userNotificationTypes: UIUserNotificationType = (.Alert | .Badge | .Sound)
            let settings:UIUserNotificationSettings = UIUserNotificationSettings(forTypes: userNotificationTypes, categories: nil)
            application.registerUserNotificationSettings(settings)
            application.registerForRemoteNotifications()
        }
}

func application(application: UIApplication,    didRegisterForRemoteNotificationsWithDeviceToken deviceToken: NSData) {
        println("didRegisterForRemoteNotificationsWithDeviceToken")
        let installation = PFInstallation.currentInstallation()
        installation.setDeviceTokenFromData(deviceToken)
        installation.saveInBackground()
}

thanks!

Answer 1

The answer is simple. If you want the user to be prompted some other time, for instance on a button press then simply move the code regarding the request into that function (or call promptUserToRegisterPushNotifications() from somewhere else).

To get a hold of the application variable outside the AppDelegate, simply do this:

let application = UIApplication.shared

Hope that helps :)

Answer 2

This is for Swift 2. I have placed promptUserToRegisterPushNotifications() in MainViewController.swift, but I have left didRegisterForRemoteNotificationsWithDeviceToken in AppDelegate because it didn't work when I place it on the same MainViewController.swift.

// In 'MainViewController.swift' file
func promptUserToRegisterPushNotifications() {
    // Register for Push Notifications

    let application: UIApplication = UIApplication.sharedApplication()

    if application.respondsToSelector(#selector(UIApplication.registerUserNotificationSettings(_:))) {
        print("registerUserNotificationSettings.RegisterForRemoteNotificatios")

        let notificationSettings = UIUserNotificationSettings(
            forTypes: [.Badge, .Sound, .Alert], categories: nil)
        application.registerUserNotificationSettings(notificationSettings) // Register for Remote Push Notifications
        application.registerForRemoteNotifications()
    }
}


// In AppDelegate
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]])
    }

    NSUserDefaults.standardUserDefaults().setObject(tokenString, forKey: "deviceToken")

    print("Device Token:", tokenString)

}

Answer 3

This is method I have written in the code and works fine once it called on launch (didFinishLaunch)

class func registerNotification() {
    if #available(iOS 10.0, *) {
        // push notifications
        UNUserNotificationCenter.current().requestAuthorization(options: [.sound, .alert, .badge]) {
            (granted, error) in
            if (granted) {
                UIApplication.shared.registerForRemoteNotifications()
            }
        }

        let center  = UNUserNotificationCenter.current()
        center.delegate = AppManager.appDel()
        center.requestAuthorization(options: [.sound, .alert, .badge]) { (granted, error) in
            if error == nil {
                UIApplication.shared.registerForRemoteNotifications()
            }
        }
    } else {
        UIApplication.shared.registerUserNotificationSettings(UIUserNotificationSettings(types: [.badge, .sound, .alert], categories: nil))
        UIApplication.shared.registerForRemoteNotifications()
    }
}