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)

Transforming shapes

In the previous recipe, Creating basic animations, you can see that SwiftUI is able to animate the change of common characteristics, such as position, color, size, and so on. But what if the feature we want to animate is not one that is part of the framework?

In this recipe, we'll create a triangular shape whose height is equal to the width times a fraction of the width; when we tap on the triangle, we set that multiplier to a random number, making the height change.

How can we instruct SwiftUI to animate the change of the multiplier? We'll see that the code needed is simple, but that the underlying engine is quite sophisticated.

Getting ready

This recipe doesn't need any external resources, so let's just create a SwiftUI project called AnimateTriangleShape in Xcode.

How to do it…

We are going to implement a triangle shape where the height is equal to the width times a multiplier.

Tapping on the shape, the multiplier...