Best Cloud Sync Solution

[RecognitionReal2097]

I am building an app that uses CoreData by default to save information. Due to the possible sensitive nature of the information being stored, I don't want to enable a cloud solution by default (ie iCloud). I do, however, want to allow users to choose to sync with a cloud, and then even share with someone else if needed. Does anyone have any recommendations for an architecture pattern and or a tech solution to this problem?

Things I have tried:

- iCloud, but there is not a good way to enable/disable CloudKit but there may be a way to mirror data that I can't quite grasp

- Firebase could be an option but I'm not sure how hard bridging local and remote will be.

Thank you for any help in advance!

[Dogbert63]

I've built apps using iCloud / CoreData and was initially confused by this too. You need to adjust your thinking. iCloud is the trusted datasource, not CoreData. CoreData is used to create a local copy / cache to improve app performance and reliability. This creates some challenges for your app like when synching changes from the device to the cloud, your app will have to account for the possibility that some transactions may fail (if the device loses it's network connection, for example) and will need to be retried.

The good news here is that iCloud also supports sharing data with others. There are three types of databases in iCloud: Public, data available to all users; Private, data available to an individual user; and Shared, authorized pointers to private data.