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)

Debugging an app based on Combine

It's a common idea that debugging reactive code is more difficult than debugging imperative code. Unfortunately, this is not completely wrong: in part, because of the nature of the code; in part, because the development tools are not sophisticated enough to follow this new paradigm.

Combine, however, implements a few convenient ways to help us better understand what happens in our streams.

In this recipe, we'll learn three techniques to debug a Combine stream.

I admit that all three are a bit basic; however, they are a starting point and should be enough to start to understand how to deal with errors in the streams.

Getting ready

Let's create a SwiftUI app called DebuggingCombineApp in Xcode.

How to do it…

Given the limited possibilities of debugging Combine, we are not implementing a sophisticated app, but a trivial three-button app that calls the three possible ways of debugging Combine:

  • Handling...