The unique identifier for this notification request.
- iOS 10.0+
- macOS 10.14+
- UIKit for Mac 13.0+Beta
- tvOS 10.0+
- watchOS 3.0+
Use this string to identify notifications in your app. For example, you can pass this string to the
remove method to cancel a previously scheduled notification.
If you use the same identifier when scheduling a new notification, the system removes the previously scheduled notification with that identifier and replaces it with the new one.
For local notifications, this property is set to the value passed to the request’s initializer (see the
init(identifier: method). For remote notifications, it is set to the value of the
apns-collapse-id key that you specified in the APNs request header when generating the remote notification. If no value is set, the system automatically assigns an identifier.