为什么在Swift 3上无法从iOS上的本地收到通知？

Question

Running on Xcode 8.3 with swift 3.1

Below is my code in AppDelegate.swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

    let center = UNUserNotificationCenter.current()

    center.requestAuthorization(options: [.alert, .sound, .badge], completionHandler: { granted, error in
        if granted {
            print("User accept notification。")
        }
        else {
            print("User don't like receive any notification!")
        }
    })

    let content = UNMutableNotificationContent()
    content.title = "Will it rain?"
    content.body = "It never rains in (Southern) California!"
    content.sound = UNNotificationSound.default()

    let trigger = UNTimeIntervalNotificationTrigger(timeInterval: 5, repeats: false)
    let request = UNNotificationRequest(identifier: "local_notification", content: content, trigger: trigger)

    center.add(request)

    return true
}

I build and run it on my iPhone and will show a message to ask me whether I like to receive any notification and I click accept.

Then, nothing happen.

I expect it will show a notification from local with some text "Will it rain" like in my code.

Answer 1

You have to make your AppDelegate to adopt UNUserNotificationCenterDelegate

In applicationDidFinishLaunching method, add this center.delegate = self

Then implement this code:

extension AppDelegate: UNUserNotificationCenterDelegate {
    func userNotificationCenter(_ center: UNUserNotificationCenter, willPresent notification: UNNotification, withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler([.alert])
    }
}

From Apple Docs:

To respond to the delivery of notifications, you must implement a delegate for the shared UNUserNotificationCenter object. Your delegate object must conform to the UNUserNotificationCenterDelegate protocol, which the notification center uses to deliver notification information to your app. A delegate is required if your notifications contain custom actions.

Reference: https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/SchedulingandHandlingLocalNotifications.html

https://developer.apple.com/reference/usernotifications/unusernotificationcenterdelegate