Instagram iOS SDK
This open source iOS library allows you to integrate Instagram into your iOS application include iPhone, iPad and iPod touch.
It's inspired by Facebook iOS SDK
Register your application on Instagram website.
Set REDIRECT URI to ig[clientId]://authorize .
Make sure you've edited your application's .plist file properly, so that your applicaition binds to the ig[clientId]:// URL scheme (where "[clientId]" is your Instagram application CLIENT ID).