Book Image

Learning Swift Second Edition - Second Edition

By : Andrew J Wagner
Book Image

Learning Swift Second Edition - Second Edition

By: Andrew J Wagner

Overview of this book

Swift is Apple’s new programming language and the future of iOS and OS X app development. It is a high-performance language that feels like a modern scripting language. On the surface, Swift is easy to jump into, but it has complex underpinnings that are critical to becoming proficient at turning an idea into reality. This book is an approachable, step-by-step introduction into programming with Swift for everyone. It begins by giving you an overview of the key features through practical examples and progresses to more advanced topics that help differentiate the proficient developers from the mediocre ones. It covers important concepts such as Variables, Optionals, Closures, Generics, and Memory Management. Mixed in with those concepts, it also helps you learn the art of programming such as maintainability, useful design patterns, and resources to further your knowledge. This all culminates in writing a basic iOS app that will get you well on your way to turning your own app ideas into reality.
Table of Contents (19 chapters)
Learning Swift Second Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Functions


So far we have called some Objective-C functions but we have not defined any yet. Let's see what the Objective-C versions are of the functions we defined in Chapter 2, Building Blocks – Variables, Collections, and Flow Control.

Our most basic function definition didn't take any arguments and didn't return anything. The Objective-C version looks similar to the following code:

func sayHello() {
    print("Hello World!");
}
sayHello()
void sayHello() {
    NSLog(@"Hello World!");
}
sayHello();

Objective-C functions always starts with the type that the function returns instead of the keyword func. In this case, we aren't actually returning anything, so we use the keyword void to indicate that.

Functions that take arguments and return values have more of a disparity between the two languages:

func addInviteeToListIfSpotAvailable
    (
    invitees: [String],
    newInvitee: String
    )
    -> [String]
{
    if invitees.count >= 20 {
        return invitees
    }
    return invitees...