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

22.1 State Properties

The most basic form of state is the state property. State properties are used exclusively to store state that is local to a view layout such as whether a toggle button is enabled, the text being entered into a text field or the current selection in a Picker view. State properties are used for storing simple data types such as a String or an Int value and are declared using the @State property wrapper, for example:

struct ContentView: View {

 

    @State private var wifiEnabled = true

    @State private var userName = ""

 

    var body: some View {

.

.

Note that since state values are local to the enclosing view they should be declared as private properties.

Every change to a state property value is a signal to SwiftUI that the view hierarchy within which the property is declared needs to be re-rendered. This involves rapidly recreating and displaying all...