The official Objective-C SDK for API v2 helps you to integrate Dropbox into your iOS and macOS apps using Objective-C.
Dropbox for Objective-C - Dropbox for Objective-C is open source on GitHub.
DBRoulette - View random photos from Dropbox.
You can add the Objective-C SDK to your project via CocoaPods, Carthage, or as an Xcode subproject.
To get started with the Objective-C SDK, check out the README in the GitHub repo, under the Get started section.
For a complete tutorial, check out the README in the GitHub repo, under the Configure your project section.
Here's the full documentation for the Objective-C SDK.