Hello,
There are numerous options for distributing push notifications (I mean native Android/iOS push notifications, not EDGE SDK or other library / framework). It depends on many factors, chief among which is your existing IT infrastructure (for example, both AWS and Azure provide their own services for that, handily linked to their authentication services, database, lambdas, etc.). You use case matters as well -- you'll use different approach for sending messages en masse, to some user groups, to specific devices, etc.
The solution that works well for us so far is Firebase Cloud Messaging (what used to be called Google Cloud Messaging or GCM), which offers free plans for push notifications and supports both Android and iOS. For Android you can configure everything right there, while for iOS you'll need to register your app with APN (you'll find all necessary details once you get to Firebase and start digging through the links). On the technical side interaction with FCM is trivial -- you just call RESTful web services, they are simple and well-documented, there's absolutely no magic, takes something like five lines of code in a single ThingWorx service.
Disclaimer: I'm not at all affiliated with Google :)
Regards,
Constantine
