Sync from particular checkpoint value

In iOS, From Particular checkpoint i should do sync instead of zero (example: i should fetch last 100 docs). Local checkpoint should be updated with this checkpoint.
CBL version : 1.4.0 - > Any Public api to set the checkpoint sequence ? How it should be done?

Can you please provide the information.

No; server sequences are opaque values, and can’t be guessed or created on the client side.

You’d need to send an HTTP request to Sync Gateway’s _changes feed to do this, and parse it yourself.

Server side it is fine.

How it should be done on client side(CBL code)?

Use your platform’s HTTP client library to send the request, and use a JSON parser to parse the response.