Book Image

Mastering macOS Programming.

By : Gregory Casamento
Book Image

Mastering macOS Programming.

By: Gregory Casamento

Overview of this book

macOS continues to lead the way in desktop operating systems, with its tight integration across the Apple ecosystem of platforms and devices. With this book, you will get an in-depth knowledge of working on macOS, enabling you to unleash the full potential of the latest version using Swift 3 to build applications. This book will help you broaden your horizons by taking your programming skills to next level. The initial chapters will show you all about the environment that surrounds a developer at the start of a project. It introduces you to the new features that Swift 3 and Xcode 8 offers and also covers the common design patterns that you need to know for planning anything more than trivial projects. You will then learn the advanced Swift programming concepts, including memory management, generics, protocol orientated and functional programming and with this knowledge you will be able to tackle the next several chapters that deal with Apple’s own Cocoa frameworks. It also covers AppKit, Foundation, and Core Data in detail which is a part of the Cocoa umbrella framework. The rest of the book will cover the challenges posed by asynchronous programming, error handling, debugging, and many other areas that are an indispensable part of producing software in a professional environment. By the end of this book, you will be well acquainted with Swift, Cocoa, and AppKit, as well as a plethora of other essential tools, and you will be ready to tackle much more complex and advanced software projects.
Table of Contents (28 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface
18
LLDB and the Command Line

Leveraging key-value observing


Key-value observing, generally abbreviated in literature to KVO, is a mechanism by which an object can observe properties of another object, so that when, for example, the data in your data model changes, that change is automatically reflected in the user interface. There are different ways for objects to notify one another in Cocoa; KVO, which is used for a number of purposes within Cocoa itself, including Cocoa bindings, Core Data, and AppleScript support, is a well-established pattern.

It doesn't take a huge amount of effort to set up, and does save you a fair amount of repetitive boilerplate code writing.

Coding for KVO

There are three steps involved in setting up KVO, and one cleanup step when we have finished observing:

  1. We need to prepare our classes for KVO.
  2. We need to let the system know when we wish to observe an object, and which change(s) we wish to observe.
  3. We need to override NSObject's method that handles the change notification.

And when we are done...