Sync content states across devices?

Question

iOS

Let's say there is an IOS application that displays some content. Each piece of content can have multiple states, such as Viewed, Favorited, Read Later, etc.
The application can be installed on several different user devices, such as iPad and iPhone.
Interested in simple ways to synchronize these states between user devices.
Are there any standard solutions and tools? Heard a bit about iCloud but not sure if it's the right one.
Is it worth asking the user to create an account (directly on the phone, just enter a username and password) and synchronize through your server?
What other options are there? Can you recommend something from your own experience?

Answer 1

Architectural solutions I see 2.
1. Your API outside processing requests for ios applications.
2. Local storage of the settings file (sqlite, etc) and uploading / uploading it to the cloud (dropbox, icloud, yadisk, etc)