Developing iOS Apps from 0 to 1
Tags: ios, oc, swift, swiftui
Published: 2024-03-13 15:50:14

## 1. Preface
iOS development is an ever-evolving field. With Apple releasing new operating systems and development tools annually, iOS developers must continuously learn and adapt to new technologies. This article aims to provide beginners with a guide to starting iOS development from scratch.

## 2. Setting Up the Development Environment

Before you begin iOS development, you need to prepare your development environment.

1. **Get a Mac computer**: iOS development requires Apple's operating system, so you need a Mac computer.
2. **Install Xcode**: Xcode is Apple's official integrated development environment (IDE) for developing iOS, macOS, watchOS, and tvOS apps. You can download Xcode for free from the Mac App Store.

## 3. Learn Objective-C, Swift, and SwiftUI Languages

Apple supports two main programming languages: Objective-C and Swift. SwiftUI is a new framework based on Swift for building user interfaces.

### 3.1. Objective-C
Objective-C is an object-oriented programming language that adds Smalltalk-style message passing to C. It has been the primary language for iOS and macOS app development for a long time.

1. **Basic Syntax**: Learn the basic syntax of Objective-C, including classes, objects, inheritance, polymorphism, etc.
2. **Memory Management**: Understand automatic reference counting (ARC) and manual reference counting (MRC).
3. **Foundation Framework**: Familiarize yourself with Objective-C's core library, such as NSString, NSArray, NSDictionary, etc.

### 3.2. Swift
Swift is a new programming language introduced by Apple in 2014. It is safer, faster, and has a more modern syntax than Objective-C.

1. **Basic Syntax**: Learn the basic syntax of Swift, including variables, constants, data types, control flow, functions, etc.
2. **Object-Oriented Programming**: Understand classes, structures, inheritance, encapsulation, and polymorphism in Swift.
3. **Advanced Features**: Master advanced concepts in Swift such as closures, protocols, generics, and error handling.

### 3.3. SwiftUI
SwiftUI is a declarative UI framework that allows developers to use Swift's concise syntax to build user interfaces.

1. **Declarative Syntax**: Learn how to use SwiftUI's declarative syntax to describe UI elements.
2. **Components and Layout**: Get familiar with various components (such as Text, Image, Button) and layout containers (such as HStack, VStack, ZStack) provided by SwiftUI.
3. **Data Flow and Binding**: Understand data flow and state management in SwiftUI, and learn how to use property wrappers like @State, @Binding, @ObservedObject, etc.

## 4. Understanding the Basics of iOS Development

After getting familiar with the programming languages, you need to understand the basics of iOS development.

1. **UIKit Framework**: If you are using Objective-C or Swift for traditional UI development, you need to learn how to use the UIKit framework to build user interfaces.
2. **Controls and Views**: Get to know common controls such as UIButton, UILabel, UITextField, UIScrollView, etc.
3. **Layout and Constraints**: Understand how to use Auto Layout to create responsive layouts.
4. **Navigation and View Controllers**: Learn how to manage navigation between multiple views and view controllers.

## 5. Practice Project
Masonry is a popular iOS layout framework that provides a concise syntax for specifying Auto Layout constraints. Here are the steps to use Masonry for code layout:

### 5.1. Install Masonry

First, you need to add Masonry to your project. If you use CocoaPods as your dependency manager, you can add the following line to your `Podfile`:

```ruby
pod 'Masonry'
```

Then run `pod install` in the terminal to install Masonry.

### 5.2. Import Masonry

In your `ViewController.swift` file, import the Masonry framework:

```swift
import UIKit
import Masonry
```

### 5.3. Create Constraints with Masonry

In your `ViewController`, use Masonry to set up the view's constraints. Here is an example of creating a label and a button and laying them out with Masonry:

```swift
class ViewController: UIViewController {
    
    let myLabel = UILabel()
    let myButton = UIButton(type: .system)
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        setupViews()
        setupConstraints()
    }
    
    func setupViews() {
        myLabel.text = "Hello, World!"
        view.addSubview(myLabel)
        
        myButton.setTitle("Tap Me", for: .normal)
        myButton.addTarget(self, action: #selector(myButtonTapped), for: .touchUpInside)
        view.addSubview(myButton)
    }
    
    func setupConstraints() {
        myLabel.mas_makeConstraints { make in
            make?.centerX.equalTo()(self.view.mas_centerX)
            make?.centerY.equalTo()(self.view.mas_centerY)
        }
        
        myButton.mas_makeConstraints { make in
            make?.top.equalTo()(myLabel.mas_bottom)?.with().offset()(20)
            make?.centerX.equalTo()(self.view.mas_centerX)
        }
    }
    
    @objc func myButtonTapped() {
        print("Button was tapped")
    }
}
```

In the code above, we first create a label and a button in the `setupViews` method and add them to the view. Then, in the `setupConstraints` method, we use Masonry's `mas_makeConstraints` method to add constraints. Masonry uses chain calls and closures, making the addition of constraints more intuitive and concise.

## 6. Mainstream UI Layout Implementations in iOS
In iOS, there are several main ways to implement UI layouts:

### 6.1. Interface Builder (Storyboard & XIB)
Interface Builder is Xcode's graphical tool that allows developers to design UIs by dragging and dropping. It supports Storyboard and XIB files.

- **Storyboard**: A Storyboard can contain multiple view controllers and their transition relationships. It is suitable for showing the flow of the app and the relationships between views.
- **XIB**: XIB files are typically used for the layout of a single view or view controller. They are suitable for simple layouts that do not require interaction between multiple view controllers.

In Interface Builder, you can use Auto Layout to set constraints for views to ensure the layout displays correctly on different screen sizes and orientations.

### 6.2. Auto Layout (Code Implementation)
Auto Layout is a constraint-based layout system that allows developers to define the size and position of views through code. With Auto Layout, you can create flexible layouts that adapt to different screen sizes and device orientations.

Implementing Auto Layout in code typically involves the following steps:
- Create views and add them to the parent view.
- Set the `translatesAutoresizingMaskIntoConstraints` property of the views to `false`.
- Use the `NSLayoutConstraint` class to create constraints.
- Add these constraints to the views.

### 6.3. Layout Anchors (Code Implementation)
Layout Anchors are a modern API for Auto Layout that provides a more concise and intuitive way to create constraints. Layout Anchors allow you to create constraints with chain calls, making the code more concise and readable.

The basic steps for using Layout Anchors are similar to those for Auto Layout, but the way to create and activate constraints is simpler.

### 6.4. UIStackView
`UIStackView` is a very convenient layout tool that can automatically manage the layout of a series of subviews. You just need to add subviews to the `UIStackView` and set its axis (horizontal or vertical), distribution, and alignment, and `UIStackView` will automatically handle the layout of the subviews.

### 6.5. Frame-Based Layout
Frame-based layout is the most basic way to layout, involving directly setting the `frame` property of views. This method requires developers to manually calculate the coordinates and sizes of each view and is generally not suitable for layouts that need to adapt to multiple screen sizes.

### 6.6. SwiftUI (iOS 13+)
SwiftUI is a brand new UI framework introduced by Apple in 2019, using a declarative syntax to build user interfaces. SwiftUI provides a new way of layout that no longer uses Auto Layout but describes the structure of the interface by combining different views and containers. SwiftUI's layout system is very powerful and can easily adapt to various screen sizes and devices.

### 6.7. Third-Party Layout Frameworks
In addition to the layout tools provided by Apple, there are some third-party layout frameworks, such as Masonry and SnapKit, which provide a more concise syntax for implementing Auto Layout. These frameworks are usually wrappers around Auto Layout, making the code easier to write and maintain.

Developers can choose the appropriate layout method based on project requirements and personal preferences. For complex layouts, Auto Layout and SwiftUI are usually better choices, while for simple static layouts, frame-based layout or UIStackView may be more direct and faster.

## 7. Important iOS Technologies

As iOS technology continues to advance, Apple frequently introduces new frameworks and tools to enhance developers' efficiency and app performance. Here are some of the latest technologies and trends in iOS development as of 2023:

### 7.1. SwiftUI
SwiftUI is a new UI framework introduced by Apple in 2019, providing a declarative Swift syntax for building user interfaces. SwiftUI aims to simplify the UI development process and provide cross-platform consistency (iOS, macOS, watchOS, and tvOS). With each year's updates, SwiftUI continues to add new components and features, making development more efficient.

### 7.2. Combine
Combine is a reactive programming framework that helps developers handle asynchronous events and data streams. The Combine framework is tightly integrated with SwiftUI, making it easier for developers to create dynamic and reactive applications.

### 7.3. WidgetKit
WidgetKit is a framework for creating widgets on the iOS home screen and notification center. These widgets can provide quick access to app content and display information without opening the app.

### 7.4. App Clips
App Clips is a technology that allows users to quickly access a part of an app's functionality without downloading the full app. Users can experience App Clips by scanning a QR code, NFC tag, or through Safari and Messages, among other methods.

### 7.5. ARKit
ARKit is Apple's augmented reality (AR) development framework, allowing developers to integrate high-quality AR experiences into iOS apps. With each update, ARKit adds new features such as body tracking, motion capture, and more.

### 7.6. Core ML
Core ML is Apple's machine learning framework, enabling developers to integrate trained machine learning models into apps. Core ML supports various model types and can perform real-time predictions on the device, protecting user privacy.

### 7.7. RealityKit
RealityKit is an advanced framework designed for AR experiences, providing features such as physics-based rendering, animation, sound effects, and collision detection. RealityKit is tightly integrated with ARKit, making it easier to create immersive AR experiences.

### 7.8. Swift Concurrency
Swift concurrency is a set of features introduced in Swift 5.5, including async/await, actors, and structured concurrency. These features aim to simplify concurrent programming, making it safer and easier to understand asynchronous code.

### 7.9. Xcode Cloud
Xcode Cloud is a cloud service announced by Apple at WWDC 2021, offering continuous integration and delivery (CI/CD) capabilities. Developers can build, test, and distribute apps in the cloud, improving development efficiency.

### 7.10. Focus on Privacy
Apple has always emphasized user privacy, so when developing iOS apps, it is important to follow best practices for privacy protection. For example, use the App Tracking Transparency framework to request user tracking permissions or use Privacy Nutrition Labels to inform users about how the app handles personal data.

## 8. The Latest iOS Technologies in 2024
Apple has made some significant updates in iOS technology for 2024. Firstly, Apple introduced a new AI model called "MGIE," which can edit images based on natural language instructions from users, expected to be applied in the iPhone 16 series and iOS 18. This AI model has the ability to interpret and execute user instructions at the pixel level, similar to Photoshop, allowing users to adjust image properties, add artistic effects, and even change backgrounds. Additionally, Apple plans to release a series of generative AI-based tools at the WWDC conference in June 2024, including an improved version of Siri. These new tools will become a key part of iOS 18. The iOS 18 system will also bring a series of AI technologies, expected to debut at WWDC 2024, and will introduce a new system design, feature enhancements, and performance improvements. These technology updates and innovations showcase Apple's efforts and direction in the field of AI.

## 9. Developing a iOS App from Scratch with Codia AI Code
To integrate Codia AI into your Figma to iOS development process, follow these instructions:
Open the link: [Codia AI Figma to code: HTML, CSS, React, Vue, iOS, Android, Flutter, ReactNative, Tailwind, Web, App](https://codia.ai/s/YBF9)

![Open the link](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/yiqdb9soc0egeb1835ad.png)

- Install the Codia AI Plugin: Search for and install the Codia AI Figma to Flutter plugin from the Figma plugin store.
- Prepare Your Figma Design: Arrange your Figma design with clearly named layers and components to ensure the best code generation results.
- Convert with Codia AI: Select your design or component in Figma and use Codia AI to instantly 

![Install the Codia AI Plugin](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/r7n2cd0pk8vk8bmvxv2u.png)

generate iOS code.

![generate iOS code](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/vnsf9k72fk6c2jhtmrg7.png)