Twitter Kit is designed to make interacting with Twitter seamless and efficient. Displaying Tweets, logging someone in, or Tweeting from your app is all made easy with Twitter Kit's components. Twitter Kit provides views for Tweets and live timelines, and a composer that makes sharing from your app simple with a few lines of code.
The VK SDK is a iOSlibrary for working with VK API, authorization through VK app, using VK functions. To authorize via VK App you need to setup a url-schema for your application, which looks like vk+APP_ID (e.g. vk1234567).
The Spotify iOSSDK allows your iOSapplication to authenticate users, as well as interact and always stay in sync with the main Spotify application running on the user’s device in the background. For the SDK to work the iOSdevice must be on iOS9 or higher and the Spotify app must be downloaded to the device.