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)

Chapter 7: Animating with SwiftUI

SwiftUI has introduced not only a new way of describing the UI elements and components but also a new way of implementing animations. In the case of animations, it needs an even more complex change of thinking. Whereas the layout concept is inherently declarative, the animation concept is inherently imperative.

When creating an animation in UIKit, for example, it is normal to describe it as a series of steps: when this happens, do that animation for 1 second, then another animation for 2 seconds.

Animation in the SwiftUI way requires us to define three parts:

  • A trigger
  • A change of data
  • A change of UI

A trigger is an event that happens, such as a button click, a slider, a gesture, and so on.

A change of data is a change of an @State variable, such as a Boolean flag.

A change of UI is a change of something that is represented visually following the change of data – for example, a vertical or horizontal offset...