Book Image

SwiftUI Cookbook - Second Edition

By : Giordano Scalzo, Edgar Nzokwe
Book Image

SwiftUI Cookbook - Second Edition

By: Giordano Scalzo, Edgar Nzokwe

Overview of this book

SwiftUI provides an innovative and simple way to build beautiful user interfaces (UIs) for all Apple platforms, from iOS and macOS through to watchOS and tvOS, using the Swift programming language. In this recipe-based cookbook, you’ll cover the foundations of SwiftUI as well as the new SwiftUI 3 features introduced in iOS 15 and explore a range of essential techniques and concepts that will help you through the development process. The cookbook begins by explaining how to use basic SwiftUI components. Once you’ve learned the core concepts of UI development, such as Views, Controls, Lists, and ScrollViews, using practical implementations in Swift, you'll advance to adding useful features to SwiftUI using drawings, built-in shapes, animations, and transitions. 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 by 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 encountered when building SwiftUI apps.
Table of Contents (17 chapters)

Chapter 9: Driving SwiftUI with Data

In this chapter, we'll learn how to manage the state of single or multiple Views. In the declarative world of SwiftUI, you should consider Views as functions of their state, whereas in UIKit, in the imperative world, you are telling a view what it has to do depending on the state. In SwiftUI, Views react to changes. SwiftUI has two ways of reaching these goals:

  • Using the binding property wrappers that SwiftUI provides
  • Using Combine, the framework that Apple introduced to implement functional reactive programming

Property wrappers are a way to decorate a property and were introduced in Swift 5.1. There are four different ways of using them in SwiftUI:

  • @State: To change state variables that belong to the same view. These variables should not be visible outside the view and should be marked as Private.
  • @ObservedObject: To change state variables for multiple but connected Views; for example, when there is a parent...