What is Swift UI?

Tech Notes
2 min readOct 26, 2023

SwiftUI is a user interface toolkit introduced by Apple at WWDC 2019 that allows developers to design and build UIs for Apple platforms using Swift code. It provides a declarative Swift syntax to create user interfaces and aims to unify the development process across all Apple devices, including iPhone, iPad, Mac, Apple Watch, and Apple TV.

Some key features and characteristics of SwiftUI include:

Declarative Syntax: Instead of specifying the intricate details of how the UI should look and behave, with SwiftUI, you declare what you want, and the system will figure out how to achieve that. For example, instead of manually managing table views, cells, and delegates, you can simply declare a List and populate it with items.

Live Preview: With the integration in Xcode, developers can instantly see the output of their SwiftUI code in a live preview, allowing for quicker iterations and adjustments.

Data-Driven: SwiftUI heavily emphasizes data-driven design. With tools like @State, @Binding, @ObservedObject, and @EnvironmentObject, developers can create reactive UIs that respond to data changes.

Adaptive and Customizable: SwiftUI automatically adapts the UI to fit different devices and screen sizes. With modifiers, you can quickly customize or tweak elements.

Animation: Animations can be easily added with just a few lines of code. SwiftUI will handle the complexities of creating smooth, interruptible animations.

Composable: Components in SwiftUI can be easily broken down into smaller views, promoting reusability and cleaner code.

Integration with UIKit: For situations where SwiftUI might not have a specific UI component or capability, it offers ways to integrate and work seamlessly with existing UIKit components.

Consistency Across Platforms: While SwiftUI is platform-agnostic to some extent, it still allows developers to fine-tune design elements for specific platforms (iOS, macOS, watchOS, tvOS) to maintain platform-specific best practices.

SwiftUI represents a significant departure from the older UIKit and AppKit frameworks, primarily because of its declarative nature and emphasis on component-based design. As SwiftUI matures, it’s becoming an increasingly central tool in Apple’s development ecosystem.

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