Catalog - UI is a reference app for native iOS user interface. It collects the standard UIKit components in one place, with parallel SwiftUI demos for the key ones, so you can see how each control looks and behaves on a real device before you build a screen around it. Tap a component to see a live demo, read its code, and copy the snippet into your project.

It is made for iOS developers, from people learning iOS UI for the first time to experienced developers who want to check a system style quickly. It is also handy when you are deciding between two controls, or between a UIKit and a SwiftUI approach, and want to compare them on the screen rather than in documentation.

The catalogue is organized into clear groups. Controls include buttons, menus, segmented controls, sliders, switches, steppers, text fields, search bars, and page controls. Pickers include the date picker, color picker, font picker, image picker, and a custom picker view. Views include activity indicators, alerts and action sheets, text views, image views, progress views, stack views, toolbars, visual effects, and a web view. The SwiftUI section offers parallel demos for key components, so you can compare UIKit and SwiftUI side by side.

Using the app is simple. Browse the list or search the full catalogue by name, then tap any component to open its live demo. Each one shows both default and custom configurations, so you can see the system look as well as some common variations. From the same screen, you can view the code snippet and copy it into your own project. Filters by tag, covering UIKit, Controls, Views, Pickers, and SwiftUI, narrow the list when you know roughly what you need. You can add items to Favorites, and a Recently Viewed list brings you back to what you were looking at.

Because the demos run on the device, you see the real behavior of each control: how a slider responds, how an alert appears, and how a picker scrolls when you actually touch it. That makes the app a quick sanity check while designing a screen, a teaching aid when explaining UI options to someone else, and a starting point when you want working code for a component you do not use often. It shows Apple's components and a few custom setups. It does not generate a full Xcode project for you.

No account is required. You open the app and start exploring. Catalog - UI is free to download from the App Store, with an optional Premium in-app purchase. It runs on iPhone and iPad and requires iOS 17.6 or later.