This LinkedIn iOS Library created by Jacob von Eyben aims to simplify API access using OAuth2. The developer recommends to fecth as a Pod from cocoapods. Another option is to download the library and import the files from folder IOSLinkedInAPI into a current application project.
I'vRead is a service for keeping track of what books you've read. Seems simple, but it can be rather useful for those of us obsessed with reading like myself. Its web site offers the service for free, and using it is already pretty simple. There isn't even another account to register for. All a user needs to do is add a specific tag, @ivread, to a Twitter post mentioning the book. It allows for some basic searches of the data on their website, but the I'vRead API is where the service really shines.