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 @Binding to pass a state variable to child Views

In the previous recipe, Using @State to drive Views behavior, you saw how to use an @State variable to change a UI. But what if we want to have another view that changes that @State variable?

Given that an array has a value-type semantic, if we pass down the variable, Swift creates a copy whose changes are not reflected in the original.

SwiftUI solves this with the @Binding property wrapper, which, in a certain way, creates a reference semantic for specific structs.

To explore this mechanism, we are going to create an extension to the TodoApp we created in the previous recipe, Using @State to drive Views behavior, where we are going to add a child view that allows the addition of a new to-do to the list.

Getting ready

The starting point for this project is the final code of the previous recipe, so you could use the same StaticTodoApp project.

If you want to keep the recipes separate, you can create a new SwiftUI...