iOS Development with SwiftUI

Acquire the Knowledge and Skills to Create iOS Applications Using SwiftUI, Xcode 13, and UIKit

Mukesh Sharma

• Publisher: BPB Publications
• Year: 2022
• eBook ISBN: 9789391030988
• Topic: Computer Science
• Subtopic: Content Management Systems
• Index: Computer Science

Learn iOS Programming Using SwiftUI Framework and Xcode

Key Features
? Demonstrates numerous examples using the SwiftUI concepts.
? A step-by-step walkthrough of the lifecycle of an Xcode 13 project.
? Access to SwiftUI development challenges and expert solutions.

Description
'iOS Development with SwiftUI' focuses on teaching and practicing the use of SwiftUI for developing iOS applications that leverage the latest iOS features.To begin, the book covers the fundamentals of SwiftUI and its core functionalities and how to write UI without having to worry much about it. It explains the fundamental Swift syntax, data types, control statements, functions, classes, and structures, as well as methods, protocols, and closures. The book covers expert tips for adding animations with a single line of code, as well as some SwiftUI transitions. Then, through a dissection of an iOS application, it teaches how to create APIs and implement API calls. It also covers widgets, App Clip development, web banner creation, and how the app communicates with the App Clip.The book will help demonstrate how to integrate XCTest into your application for both UI and unit testing and how to write your test case and prepare the application for general use.At the end of the book, you will be able to write an iOS application in SwiftUI and gain some experience to call API or web services using combine.

What you will learn
? Learn to use the feature 'Combine' in the application and call various APIs.
? Understand data flow and stacks, including VStack, HStack, and ZStack.
? Understand and practice how to share the data between the app and extensions.
? Work with the latest iOS features such as App Clip and Widgets.
? Become well versed with Xcode 13 and UIKit while using it with SwiftUI.

Who this book is for
This book caters to SwiftUI developers, iOS developers, and students who want to build good proficiency in the entire process of iOS application development. Knowing basic programming concepts would be good, although not mandatory.

Table of Contents
1. What is SwiftUI
2. Basics of Swift
3. Anatomy of the Basics of SwiftUI Projects
4. Introduction to SwiftUI Basic Controls and User Input
5. State Properties, Observable, Environment Objects, and Combine Framework
6. Stacks of Views Using VStack, HStack, And ZStack
7. Work with Lists and Navigation.
8. SwiftUI with UIKit
9. UIKit with SwiftUI
10. UI Logic of the MVVM Architecture and Networking
11. Drawing in SwiftUI
12. Animations and Transitions in SwiftUI
13. App Clip
14. Widgets

CHAPTER 1

What is SwiftUI?

Introduction

In this chapter, we will give you a detailed introduction to Apple’s newest app development framework SwiftUI, after a few general words about SwiftUI, will review its architecture.

WWDC is always a source of exciting stuff for developers; everyone waits with bated breath to see what new tech is being introduced by Apple. The most recent pioneering piece of tech released by Apple was in 2014 when Apple released Swift in addition to Apple’s currently used programming language, Objective-C. Since its release, Swift has updated and evolved, eventually becoming one of today’s most beloved and powerful programming languages.

SwiftUI was announced by Apple at WWDC19 and is described as “SwiftUI is an innovative, exceptionally simple way to build user interfaces across all Apple platforms with the power of Swift” and that’s true with SwiftUI; it’s surprisingly simple to build apps just like you imagine them to look.

Structure

This chapter covers the details of SwiftUI:

• Introduction to SwiftUI
• The SwiftUI architecture
• Opaque types
• SwiftUI for all Apple products

Objective

The objective of this chapter is to explain SwiftUI, SwiftUI architecture, and technical requirements to run the SwiftUI on macOS. For this book, our focus is on developing iOS applications for the iPhone.

SwiftUI follows a declarative syntax approach, meaning that we depict in code how our interface should look:

Figure 1.1: SwiftUI example with preview

Technical requirements for running SwiftUI

SwiftUI shipped with Xcode 11, which you can download for free from the Mac App Store. Note that SwiftUI is only compatible with running at least macOS Catalina and BigSur or later versions.

When you start creating your project with Xcode 13, you have to select an alternative to storyboard, select the SwiftUI from the dropdown, as seen in the following screenshot:

Figure 1.2: Showing selection option for SwiftUI

This approach to app creation is a true cross-Apple platform and, along with the Catalyst launch, with just a few taps, the iPadOS app is now becoming a true native macOS app, a choice that just wasn’t possible with UIKit.

Introduction to SwiftUI

The SwiftUI framework is quite different from Cocoa. It operates on a programming paradigm that is completely unlike Cocoa. In SwiftUI, there is no storyboard, no nibs, and no outlets. There is no UIViewController, not even a UIView. Text is a struct, and View is just a protocol. A SwiftUI View is extremely lightweight.

Declarative

The declarative syntax is a paradigm of programming that allows you to write more formal and procedural code. The declarative syntax is a way of describing the code you want to write, without worrying about how it’s going to be implemented. Due to SwiftUI’s declarative nature of programming, it changes the paradigm of UI development by revealingly reducing lines of code.

With iOS 13, developers were using UIKit with an imperative technique of UI development. It means that a developer needs to handle the events, UI transition, or maintain states by writing additional lines of code every single time an event should be reflected in the UI. With this technique, apps become more complicated and less readable.

Imperative syntax:

let labelText = UILabel(frame: CGRect(x:0, y:0, width:120, height:120))

labelText.text = “Understanding SwiftUI”

labelText.textColor = UIColor.red

labelText.backgroundColor = UIColor.green

labelText.font = UIFont(name: “Consolas”, size: 26)

self.view.addSubview(labelText)

Declarative Syntax (SwiftUI code):

Text(“Understanding SwiftUI”)

.foregroundColor(.blue)

.background(Color.red)

.font(.largeTitle)

In the preceding code, we see two syntax structures of codes for a similar output. One is imperative nature, and the other is a declarative SwiftUI approach with not so much code but rather more comprehensible what is the issue with the imperative methodology is the developer need to assemble the code, over and over, to check the yield of the coding But in SwiftUI, revelatory user can see the coding yield promptly on the preview.

Output:

Figure 1.3: Output of declarative syntax

With declarative methodology, Apple permits the developer to declare all states for the view at once, no longer needing to write the code for managing the states.

SwiftUI completed this task for the developer to declare rules at the very beginning. The only task left for the developers is to shape the showcase model and refresh.SwiftUI will refresh the UI.

When we used storyboards to make a UI, we got a huge XML document with complicated code that was hard to read. Lately, this XML document has been converted to machine code, and now no more complicated XML in SwiftUI.

Automatic

SwiftUI has no extensive needs for Interface Builder; Canvas, a responsive interface editor, replaced it. When writing code, the visual part in Canvas is automatically generated. When we use SwiftUI previews during development, you can quickly create more flexible and maintainable apps. It allows you to manage themes easily. Developers can easily add dark mode to their apps and set it as the default theme, and users can easily equip dark mode.

It offers a Live Preview. This is a very opportune and reformer way to see the results of code execution in real-time without having to build.SwiftUI preview and also shows our designs in multiple screen sizes at the same time. This speeds up development.

The SwiftUI architecture

The Swift language is an open source, but SwiftUI is not open source and overseen by Apple. When you’ve taken in the nuts and bolts of SwiftUI, you’v...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Dedication Page
• About the Author
• About the Reviewer
• Acknowledgements
• Preface
• Errata
• Table of Contents
• 1. What is SwiftUI?
• 2. Basic of Swift
• 3. Anatomy of a SwiftUI projects
• 4. Introduction to SwiftUI Basic Controls and User Input
• 5. State Properties, Observable, Environment Objects, and Combine Framework
• 6. Stacks of Views Using VStack, HStack, And ZStack
• 7. List and Navigation
• 8. SwiftUI in UIKit
• 9. UIKit in SwiftUI
• 10. Animation and Transitions
• 11. Drawing in SwiftUI
• 12. MVVM and Networking Using Combine
• 13. App Clip
• 14. Widgets
• Index