NSURLSession design considerations with CouchDB backend

🎤 General Discussion iOS
1

I’m seeking suggestions for migrating legacy code from ASIHTTPRequest to NSURLSession in Objective-C on iOS. The legacy code is one huge method with many return statements, but I would like something more modern with fewer return statements and small methods. As the title states, the backend is CouchDB; documents are keyed by uuid.

There are five use cases:

  1. GET UUID for a post to create a unique payload id
  2. PUT JSON payload using the UUID
  3. GET _rev for UUID (required for follow-on payload updates)
  4. PUT JSON payload using UUID and _rev, again for updates
  5. PUT a set of image(s) using UUID and _rev

Is there a common idiom for cascading requests when there are dependencies. For example, item 3 depends upon item 2 which in-turn depends upon item 1?

Thanks in advance for your suggestions.