Phantomxm2021/unity-swiftui

unity-swiftui

This is a reference project for those that want to use Unity as a Library in their SwiftUI iOS app. Unity's existing iOS documentation only demonstrates UAAL with UIKit/Objective-C projects and lacks illustrative examples of native-to-unity state flow, control of the Unity view, and automated integration of Unity's build output.

Requirements

• Physical device with iOS 17.5 or later.
• Unity Editor 2022.3.36f1 - latest LTS at time of this writing - with iOS build support installed in Unity Hub.

Instructions

1. Clone repository

   git clone https://github.com/bdeweygit/unity-swiftui.git
   cd unity-swiftui

2. Create build folder for Unity project

   mkdir -p UnityProject/Builds/iOS

3. Open Unity project

   • Use Unity Hub to open UnityProject directory.
   • Go to File > Build Settings.
   • In platform menu, select iOS and click Switch Platform.
   • Click Build and choose Builds/iOS folder you created earlier.

4. Open integration workspace

   • Use Xcode to open integration.xcworkspace file.

5. Configure SwiftUI project

   • Edit UnitySwiftUI target's signing settings with valid bundle identifier and signing team ID.
   • Switch to UnitySwiftUI scheme.

6. Run app on a physical device

   • Connect your physical device to Xcode.
   • Build and run UnitySwiftUI scheme to your device.

Key features

• Control of Unity view as a SwiftUI element that can be repositioned and resized. Unity's documentation says "Unity as a Library only supports full-screen rendering, and doesn’t support rendering on part of the screen." We have fixed this limitation.
• Touches and gestures on Unity view are processed within Unity.
• Restarting the Unity player.
• State data is sent from native Swift to Unity C# as a struct with members including string, boolean, floating point, integer, and MTLTexture types.

Key files

SwiftUI Project

• Unity.swift: Class for controlling Unity framework and native-to-unity state flow.
• ContentView.swift: UI demonstrating Unity view as a SwiftUI element and controls for layout and state.

Unity Project

• NativeStateManager.cs: Class for receiving and storing native state data.
• RootBehavior.cs: Script that renders content - a cube and a spotlight - reacting to state updates and touch events.
• NativeState.h, NativeState.m: Plugin enabling flow of state data from native Swift to Unity C#.
• UnityFramework.modulemap: Custom modulemap for plugin interoperability with Swift.
• PostProcessBuild.cs: Script automating integration of Unity generated Xcode project.

Known issues

• After building Unity project, Xcode workspace may not always reflect latest files and be unable to build. Close and reopen workspace to fix this bad state.
• When running while attached to Xcode, there may be some noticeable delay between device orientation change and UI layout. There should be no such delay when running detached.