---
title: "Use SwiftUI with AppKit and UIKit"
description: "Incrementally adopt SwiftUI in AppKit or UIKit apps using Observation, hosting views and menus, gesture recognizer representables, and SwiftUI scenes."
shoutout: "Unofficial, made with love by Superwall - the best way to monetize your apps."
category: "SwiftUI & UI Frameworks"
---

# Use SwiftUI with AppKit and UIKit


[Watch on Apple Developer](https://developer.apple.com/videos/play/wwdc2026/272/)

Incrementally adopt SwiftUI in AppKit or UIKit apps using Observation, hosting views and menus, gesture recognizer representables, and SwiftUI scenes.

## TL;DR

- Use `@Observable` models to let AppKit and UIKit automatically invalidate drawing, layout, constraints, and other UI updates based on property reads.
- Embed new SwiftUI components in an existing AppKit hierarchy with `NSHostingView`; the session demonstrates replacing slider-based drawing with a SwiftUI `Canvas` color picker.
- Reuse existing AppKit gesture recognizers in SwiftUI with `NSGestureRecognizerRepresentable`, and build AppKit main-menu content from SwiftUI using `NSHostingMenu`.
- Add complete SwiftUI scenes from an `NSApplicationDelegate` with `NSHostingSceneRepresentation`, including `MenuBarExtra` and `Settings` scenes.

## Incremental SwiftUI adoption strategy

SwiftUI is intended to coexist with AppKit and UIKit, so existing apps can adopt it feature by feature rather than through a rewrite. The session uses a macOS lighting-control app as the running example, but the general approach applies across Apple platforms.

The recommended migration path starts with shared observable models, then moves individual controls, menus, gestures, and whole scenes to SwiftUI where they make sense.

- Start by moving shared mutable UI state into `@Observable` model types.
- Use SwiftUI for new or substantially rewritten UI components, especially when drawing and interaction code would change significantly.
- Keep the existing AppKit or UIKit lifecycle and view hierarchy where it is still working.
- Adopt SwiftUI scenes for new windows, settings, or menu bar extras without converting the whole app.

## Observation in AppKit and UIKit

AppKit can automatically track reads from `@Observable` model properties during supported view and controller update methods. When those properties change, the relevant views update without manually setting `needsDisplay`.

The example replaces manual invalidation between hue, saturation, and brightness sliders with a shared `ColorModel`. AppKit tracks property reads inside drawing methods such as `NSSliderCell.drawKnob` and redraws when accessed values change.

- AppKit observation applies to `NSView.draw(_:)`, drawing paths called by view drawing such as `NSSliderCell` drawing methods, `updateConstraints()`, `layout()`, `updateLayer()`, and related `NSViewController` methods.
- UIKit has similar Observation tracking across `UIView`, `UIViewController`, and additional UIKit types such as controls and collection view cells.
- Back deploy AppKit integration to macOS 15 with `NSObservationTrackingEnabled` in `Info.plist`.
- Back deploy UIKit integration to iOS 18 with `UIObservationTrackingEnabled`; tracking is enabled by default in the 2026 releases and later.

### Observable model shared by AppKit and SwiftUI

Adding `@Observable` makes mutable properties participate in Observation so AppKit, UIKit, and SwiftUI can react to changes.

```swift
import Observation

@Observable
@MainActor
final class ColorModel {
    var hue: Double = 0.6
    var saturation: Double = 1.0
    var brightness: Double = 1.0
}
```

## Host SwiftUI controls inside AppKit

When a component's rendering and interaction model changes substantially, rebuilding it in SwiftUI can be simpler than evolving the existing AppKit view. The sample replaces three custom slider cells with a circular HSB color picker drawn using SwiftUI `Canvas`.

`Canvas` provides an immediate-mode drawing model similar to AppKit or UIKit drawing: each redraw receives a fresh `GraphicsContext`, and code issues strokes, fills, transforms, and filters. Existing Core Graphics drawing can be reused through `withCGContext`.

- The SwiftUI color picker uses the same `@Observable` `ColorModel` as the previous AppKit implementation.
- The picker draws a hue ring, saturation and brightness semicircles, and a center color preview.
- The SwiftUI view is embedded in the existing `NSView` hierarchy using `NSHostingView`, which is itself an `NSView` subclass.

### Embed a SwiftUI view in AppKit

Use `NSHostingView` to place a SwiftUI component inside an AppKit view hierarchy.

```swift
NSHostingView(
    rootView: HSBColorPicker(model: model)
)
```

### SwiftUI Canvas shape of the color picker

The session's full sample draws with `Canvas`; this abbreviated version shows the immediate-mode drawing structure.

```swift
struct HSBColorPicker: View {
    var model: ColorModel

    var body: some View {
        Canvas { context, size in
            let metrics = PickerMetrics(size: size)
            drawPicker(in: &context, metrics: metrics,
                       hue: model.hue,
                       saturation: model.saturation,
                       brightness: model.brightness)
        }
        .contentShape(Circle())
        .aspectRatio(1, contentMode: .fit)
    }
}
```

## Bring AppKit gestures and menus into SwiftUI

Existing AppKit gesture recognizers do not need to be rewritten as SwiftUI gestures. `NSGestureRecognizerRepresentable` lets a SwiftUI view create and handle an `NSGestureRecognizer` subclass, then attach it with the standard `.gesture` modifier.

The sample adds a Force Click gesture that resets saturation and brightness to full intensity. Because Force Click is not available on every input device, the same action is also exposed through a SwiftUI-built main menu with keyboard shortcuts.

- Implement `makeNSGestureRecognizer(context:)` to create the AppKit recognizer.
- Implement `handleNSGestureRecognizerAction(_:context:)` to respond when the recognizer fires.
- Attach the representable gesture to a SwiftUI view using `.gesture`.
- Build menu content as a SwiftUI `View`, then wrap it in `NSHostingMenu` and assign it as an AppKit `NSMenuItem` submenu.

### Wrap an AppKit gesture recognizer for SwiftUI

`NSGestureRecognizerRepresentable` reuses an existing AppKit recognizer from a SwiftUI view.

```swift
struct ForceClickReset: NSGestureRecognizerRepresentable {
    var model: ColorModel

    func makeNSGestureRecognizer(context: Context) -> ForceClickGestureRecognizer {
        ForceClickGestureRecognizer()
    }

    func handleNSGestureRecognizerAction(_ recognizer: ForceClickGestureRecognizer,
                                         context: Context) {
        withAnimation {
            model.saturation = 1
            model.brightness = 1
        }
    }
}
```

### Host SwiftUI menu content in the AppKit main menu

`NSHostingMenu` is an `NSMenu` subclass, so it can be inserted into an existing AppKit menu tree.

```swift
let colorMenu = NSHostingMenu(rootView: ColorMenu(model: colorModel))
colorMenu.title = "Color"

let colorMenuItem = NSMenuItem()
colorMenuItem.submenu = colorMenu
mainMenu.addItem(colorMenuItem)
```

## Add SwiftUI scenes from an AppKit lifecycle

SwiftUI scenes can be added dynamically from an existing AppKit app without moving to the SwiftUI app lifecycle. The sample uses `NSHostingSceneRepresentation` from `NSApplicationDelegate.applicationWillFinishLaunching` to add a `MenuBarExtra` scene and a `Settings` scene.

The menu bar extra provides quick access to light controls. The settings window contains a toggle bound to app state that inserts or removes the menu bar extra, and `NSHostingSceneRepresentation` exposes an environment action for opening settings programmatically.

- Create an `NSHostingSceneRepresentation` with one or more SwiftUI scenes.
- Register it with `NSApplication.shared.addSceneRepresentation(...)`.
- Use `MenuBarExtra(..., isInserted:)` to let state control whether the menu bar item is present.
- Use the representation's environment `openSettings()` action from an `@IBAction` when an AppKit menu command should open the SwiftUI settings scene.

### Register SwiftUI scenes from an AppKit app delegate

`NSHostingSceneRepresentation` bridges SwiftUI scenes into an app that still uses `NSApplicationDelegate`.

```swift
func applicationWillFinishLaunching(_ notification: Notification) {
    let scenes = NSHostingSceneRepresentation {
        LightMenuBarExtra(appModel: model)
        LightSettings(appModel: model)
    }

    NSApplication.shared.addSceneRepresentation(scenes)
    openSettingsAction = { scenes.environment.openSettings() }
}

@IBAction func openSettings(_ sender: Any?) {
    openSettingsAction?()
}
```

## Related Sessions

- [Compose advanced graphics effects with SwiftUI](https://wwdc.ai/2026/322)
- [What's new in UIKit](https://developer.apple.com/videos/play/wwdc2025/243)
- [Bring multiple windows to your SwiftUI app](https://developer.apple.com/videos/play/wwdc2022/10061)
- [Use SwiftUI with AppKit](https://developer.apple.com/videos/play/wwdc2022/10075)
- [Use SwiftUI with UIKit](https://developer.apple.com/videos/play/wwdc2022/10072)
- [Add rich graphics to your SwiftUI app](https://developer.apple.com/videos/play/wwdc2021/10021)

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