Optionals are one of the most important concepts to grasp when learning Swift.
Learn how to apply interactive filter effects to your images on iOS using Core Image.
Learn how to build small utility applications that live in the system menubar.
Known as categories in Obj-C, extensions allow you to easily extend class functionality.
Learn to use storyboards to visually lay out and connect the views in your Mac app.
Learn to use the new live scripting environment called Playground in Xcode 6.