First, technologies such as CoreData and sqlite are usually local storage for devices. Local device storage will not provide you with cloud storage.
Parse.com is a quick way for devices to access cloud storage and grow rapidly. Especially useful for games and other mobile applications for accessing cloud data through the application key and application key. This is a simple repository to avoid creating your own backend if it fills all your needs and requirements.
When you go to the tiered cloud backend, where you minimize your own services and multiple devices accessing your cloud application, you need to take a look at the disclosure of your web API. Providing a RESTful API over http is great for devices and web clients. Providing data as JSON is especially convenient for the Internet and is easily consumed by devices.
These cloud service web service endpoints have some kind of backend storage that is optimized for simultaneous access by multiple clients. This is usually an SQL server such as MySQL, SQLServer, etc. Or NoSQL , for example mongodb , couchDB , etc.
Some api technologies for web interfaces to learn:
Some background storage technologies that need to be explored:
If the data is used by many many clients with multiple tenants, the backend can be scaled (more and more) or delayed. Facing is where data for several users is divided into many databases or data warehouses with some kind of search algorithm for search queries for where user data is stored. Server servers api for web servers abstract server storage.
Finally, you will need some kind of caching / quick search technology (if you are successful :):
- Redis : quick memory access through sockets
- memcached : facebook uses - a simple key value in memory caching on many interface servers.
Your question is an open-ended question with a wide range of questions, so start by searching on many of these terms and technologies.
Each of these links will have resources and tutorials. Get a cloud-based virtual machine, play with everyone and decide what works best for your needs. No size fits all solutions.