How do I get Infobip's unique (push registration) ID? - infobip/mobile-messaging-sdk-ios GitHub Wiki
In order to get Infobip's unique push registration identifier issued by the server you need to implement the following code:
if let pushRegistrationId = MobileMessaging.getInstallation()?.pushRegistrationId {
    // your business logic
}
This identifier:
- matches one to one with APNs cloud token of the particular application installation
 - is only available after 
MMNotificationRegistrationUpdatedevent - does not change for the whole lifetime of the application installation