Book Image

Mastering Swift 5.3 - Sixth Edition

By : Jon Hoffman
Book Image

Mastering Swift 5.3 - Sixth Edition

By: Jon Hoffman

Overview of this book

Over the years, Mastering Swift has proven itself among developers as a popular choice for an in-depth and practical guide to the Swift programming language. This sixth edition comes with the latest features, an overall revision to align with Swift 5.3, and two new chapters on building swift from source and advanced operators. From the basics of the language to popular features such as concurrency, generics, and memory management, this in-depth guide will help you develop your expertise and mastery of the language. As you progress, you will gain practical insights into some of the most sophisticated elements in Swift development, including protocol extensions, error handling, and closures. The book will also show you how to use and apply them in your own projects. In later chapters, you will understand how to use the power of protocol-oriented programming to write flexible and easier-to-manage code in Swift. Finally, you will learn how to add the copy-on-write feature to your custom value types, along with understanding how to avoid memory management issues caused by strong reference cycles. By the end of this Swift book, you will have mastered the Swift 5.3 language and developed the skills you need to effectively use its features to build robust applications.
Table of Contents (23 chapters)
21
Other Books You May Enjoy
22
Index

Defining a parameter's default values

We can define default values for any parameter by using the equal to operator (=) within the function definition when we declare the parameters. The following example shows how to declare a function with a parameter's default values:

func sayHello(name: String, greeting: String = "Bonjour") { 
    print("\(greeting) \(name)")
}

In the function declaration, we have defined one parameter without a default value (name:String) and one parameter with a default value (greeting: String = "Bonjour"). When a parameter has a default value declared, we can call the function with or without setting a value for that parameter. The following example shows how to call the sayHello() function without setting the greeting parameter, and also how to call it when you do set the greeting parameter:

sayHello(name:"Jon") 
sayHello(name:"Jon", greeting: "Hello")

In the sayHello(name...