Book Image

SwiftUI Essentials – iOS 14 Edition

By : Neil Smyth
Book Image

SwiftUI Essentials – iOS 14 Edition

By: Neil Smyth

Overview of this book

Do you want to create iOS apps with SwiftUI, Xcode 12, and Swift 5.3, and want to publish it on the app store? This book helps you achieve these skills with a step-by-step approach. This course first walks you through the steps necessary to set up an iOS development environment together and introduces Swift Playgrounds to learn and experiment with Swift—specifically, the Swift 5.3 programming language. After establishing key concepts of SwiftUI and project architecture, this course provides a guided tour of Xcode in SwiftUI development mode. The book also covers the creation of custom SwiftUI views and explains how these views are combined to create user interface layouts, including the use of stacks, frames, and forms. One of the more important skills you’ll learn is how to integrate SwiftUI views into existing UIKit-based projects and explain the integration of UIKit code into SwiftUI. Finally, the book explains how to package up a completed app and upload it to the app store for publication. Along the way, the topics covered in the book are put into practice through detailed tutorials, the source code for which is also available for download. By the end of this course, you will be able to build your own apps for iOS 14 using SwiftUI and publish it on the app store. The code files for the book can be found here: https://www.ebookfrenzy.com/retail/swiftui-ios14/
Table of Contents (56 chapters)
56
Index

9.7 Local and External Parameter Names

When the preceding example functions were declared, they were configured with parameters that were assigned names which, in turn, could be referenced within the body of the function code. When declared in this way, these names are referred to as local parameter names.

In addition to local names, function parameters may also have external parameter names. These are the names by which the parameter is referenced when the function is called. By default, function parameters are assigned the same local and external parameter names. Consider, for example, the previous call to the buildMessageFor method:

let message = buildMessageFor(name: "John", count: 100)

As declared, the function uses “name” and “count” as both the local and external parameter names.

The default external parameter names assigned to parameters may be removed by preceding the local parameter names with an underscore (_) character as...