UIKit is the framework that you'll user most often when developing iOS applications. It defines the core components of an iOS application, from labels and buttons to table views and navigation controllers. In this article, not only will we start our exploration of the UIKit framework, we will also explore the internals of an iOS project and the basic building blocks of iOS applications.
Source files for the Envato Tuts+ tutorial: iOS From Scratch With Swift: First Steps with UIKit
Read this tutorial on Envato Tuts+.