Two different approaches to building UI
SwiftUI and UIKit are both Apple UI frameworks, but they approach interface development from different directions.
SwiftUI uses a declarative model. You describe what the interface should look like for the current state, and SwiftUI handles the process of updating the rendered interface.
UIKit follows a more imperative model. Developers work directly with views, view controllers, lifecycle methods and UI mutations.
SwiftUI
Describe the UI from state and composition. The framework manages much of the update process.
UIKit
Build and manage views directly through controllers, objects and imperative operations.
Why SwiftUI feels different
Consider a simple piece of state. In SwiftUI, a change to that state can cause the view's body to be recalculated. The developer focuses primarily on the relationship between state and UI.
The important idea is not the button itself. The important idea is that the UI describes the current state of the application.
Where UIKit still makes sense
UIKit remains highly relevant in existing applications and in areas where its mature APIs and ecosystem are useful.
- Large existing UIKit codebases.
- Teams maintaining established view-controller architectures.
- Components or APIs that are primarily UIKit-oriented.
- Projects where rewriting working UI would create unnecessary risk.
SwiftUI is especially useful for new UI
For a new Swift application, SwiftUI can provide a clean way to compose interfaces and model UI state.
It also works naturally with modern Swift features and can make reusable components straightforward to define.
You don't have to choose only one
One of the most important things to understand is that SwiftUI and UIKit are not mutually exclusive.
A SwiftUI application can host UIKit components, and UIKit applications can embed SwiftUI views. This allows teams to introduce SwiftUI gradually instead of rewriting everything at once.
What about performance?
Performance should be evaluated against the actual application rather than assuming one framework is universally faster.
The architecture, amount of work performed, data flow, rendering behavior and implementation details can matter more than simply choosing SwiftUI or UIKit.
What should a beginner learn?
If you're starting modern iOS development, learning SwiftUI first can give you a useful introduction to state-driven UI composition.
After that, learning UIKit is still valuable. It gives you the ability to understand and modify a large amount of existing iOS software.
Learn Swift → learn SwiftUI → build projects → understand UIKit → learn how to integrate both.
The real decision is about complexity
Instead of asking which framework is universally better, ask which approach makes the particular screen or project easier to understand and maintain.
For a new SwiftUI application, introducing UIKit may be unnecessary complexity. For a mature UIKit application, rewriting every screen into SwiftUI may create unnecessary work.
The strongest iOS developer is not limited to one framework. They understand the trade-offs and can work with both when the project requires it.
Build with Swift.
Use SwiftBuilder to generate Swift and SwiftUI code, experiment with interfaces and iterate on your application.
Download SwiftBuilder