Hello,
Seem that you will need a application, serve as backend server, that process heavily requests and provide RESTful services for iOS and Android apps.
For that, I would like to propose the following things:
- you build your client apps (iOS, Android, ...)
- those apps create and maintain a connection to an application server (this project)
- the application server is responsible to talk with database, process request, render result and push back to client apps.
- in detail, application server contain all users management, list creation, monitoring progress, calculation, push notification ... and expose those functionality via APIs so that client apps can call. One application server can serve many client apps, no matter which platform it built.
- development: I prefer agile so will deliver code (nearly) everyday so that you can see what's going on and give feedbacks quickly. Test code (TDD) also be written for most of the functions. In case you demand only list, user, progress and devices management, the first working prototype can be up and run in 1 week, final product in next 4 or 5 weeks, included all testing and documentation.
Because of limitation of freelancer input text box, I can only draft the big picture. Please let me know if that is what you expected or did I miss any important thing? I think there's a lot of thing that need to be clear.
Thank you,