CoreData vs. FireBase vs. Realm

I am developing my app using a project-based approach to learning. I am designing an app that analyzes user motion (from the phone first, then the watch.)

The first step is to use CoreMotion (which I have done). The next step is to save that data somehow (for persistence) so I can do some calculations and present it in various ways.

The user would open the app - select the date (when the movement was recorded) and then present the data on a different screen. The user would have the option of deleted previous files or starting new sessions where the data can be recorded.

I am trying to learn all the different components of what I need to use. I am now trying to sort out how to save the data and am not sure what to learn next.

The ultimate goal is to use the watch and send the data from the watch to the phone but I need to learn the different components (CoreMotion, CoreData or Firebase) first.

Any advice would be helpful.

CoreData, Firebase, and Realm are all different.

CoreData and Realm are both frameworks where you can save data locally on the device.

Firebase is used to save data in the cloud.

I’m not sure about the watch communication to the iPhone, because watch apps are supposed to stand alone independent of the iPhone.

You may want to look into CloudKit which is similar to Firebase (it’s in the cloud) but CloudKit is Apple’s one framework.

As is CoreData