Book Image

SwiftUI Cookbook

By : Giordano Scalzo, Edgar Nzokwe
Book Image

SwiftUI Cookbook

By: Giordano Scalzo, Edgar Nzokwe

Overview of this book

SwiftUI is an innovative and simple way to build beautiful user interfaces (UIs) for all Apple platforms, right from iOS and macOS through to watchOS and tvOS, using the Swift programming language. In this recipe-based book, you’ll work with SwiftUI and explore a range of essential techniques and concepts that will help you through the development process. The recipes cover the foundations of SwiftUI as well as the new SwiftUI 2.0 features introduced in iOS 14. Other recipes will help you to make some of the new SwiftUI 2.0 components backward-compatible with iOS 13, such as the Map View or the Sign in with Apple View. The cookbook begins by explaining how to use basic SwiftUI components. Then, you’ll learn the core concepts of UI development such as Views, Controls, Lists, and ScrollViews using practical implementation in Swift. By learning drawings, built-in shapes, and adding animations and transitions, you’ll discover how to add useful features to the SwiftUI. When you’re ready, you’ll understand how to integrate SwiftUI with exciting new components in the Apple development ecosystem, such as Combine for managing events and Core Data for managing app data. Finally, you’ll write iOS, macOS, and watchOS apps while sharing the same SwiftUI codebase. By the end of this SwiftUI book, you'll have discovered a range of simple, direct solutions to common problems found in building SwiftUI apps.
Table of Contents (15 chapters)

Using @State to drive Views behavior

As mentioned in the introduction, when a state variable belongs only to a single view, its changes are bound to the components using the @State property wrapper.

To understand this behavior, we are going to implement a simple To-do List app, where a static set of to-dos are changed to 'done' when we tap on the row.

In the next recipe, Using @Binding to pass a variable to child Views, we'll expand on this recipe, adding the possibility of adding new to-dos.

Getting ready

Let's start the recipe by creating a SwiftUI app called StaticTodoApp.

How to do it…

To demonstrate the use of the @State variable, we are going to create an app that holds its state in a list of Todo structs: each Todo can be either undone or done, and we change its state by tapping on the related row.

When the user taps on one row in the UI, they change the done state in the related Todo struct:

  1. Let's start by adding...