Book Image

iOS 15 Programming for Beginners - Sixth Edition

By : Ahmad Sahar, Craig Clayton
5 (1)
Book Image

iOS 15 Programming for Beginners - Sixth Edition

5 (1)
By: Ahmad Sahar, Craig Clayton

Overview of this book

With almost 2 million apps on the App Store, iOS mobile apps continue to be incredibly popular. Anyone can reach millions of customers around the world by publishing their apps on the App Store. iOS 15 Programming for Beginners is a comprehensive introduction for those who are new to iOS. It covers the entire process of learning the Swift language, writing your own app, and publishing it on the App Store. Complete with hands-on tutorials, projects, and self-assessment questions, this easy-to-follow guide will help you get well-versed with the Swift language to build your apps and introduce exciting new technologies that you can incorporate into your apps. You'll learn how to publish iOS apps and work with Mac Catalyst, SharePlay, SwiftUI, Swift concurrency, and much more. By the end of this iOS development book, you'll have the knowledge and skills to write and publish interesting apps, and more importantly, to use the online resources available to enhance your app development journey.
Table of Contents (32 chapters)
1
Part 1: Swift
10
Part 2: Design
15
Part 3: Code
25
Part 4: Features

Exploring constants and variables

Now that you know about the simple data types that Swift supports, let's look at how to store them, so you can perform operations on them later.

You can use constants or variables to store data. Both are containers that have a name, but a constant's value can only be set once and cannot be changed after it has been set, whereas a variable's value can be changed at any time.

You must declare constants and variables before you use them. Constants are declared with the let keyword whereas variables are declared with the var keyword.

Let's explore how constants and variables work by implementing them in your playground. Follow these steps:

  1. Add the following code to your playground to declare three constants:
    let theAnswerToTheUltimateQuestion = 42 
    let pi = 3.14159
    let myName = "Ahmad Sahar"
  2. Click the Play/Stop button to run it.

In each case, a container is created and named, and the assigned value...