Understanding ARC and Memory Management

Swift has a very particular and almost unique memory management strategy: Automatic Reference Counting (ARC). When using ARC, the compiler will inject memory management code for us, but it's very easy to write poor, leaky code, either on purpose or by accident. In this chapter, we'll cover all of the basics for good memory management in Swift. From its origins in Objective-C, to the pre-ARC era, to today, we'll look at how to properly manage our memory and object life cycles. We'll also explore the powerful tools available with Xcode to track memory usage, leaks, cycles, and other defects, through the inspector and the leaks instrument.

In this chapter, we'll cover the following topics:

• A brief history of reference counting
• What is ARC?
• Debugging memory
• Leaks, cycles, and dangling references