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This page applies to SpatialOS 10.4. It hasn't been upgraded to SpatialOS 11 yet.

Building for iOS targets in Unity

This page describes the required steps for a SpatialOS Unity project to support iOS build targets.


This guide assumes that you have an existing SpatialOS project, which you are intending to add iOS support using Unity.

First, determine if you have automatically generated build scripts for Unity turned on:

  1. Locate the workers/unity folder of your SpatialOS project.
  2. Open spatialos.UnityClient.worker.json in a text editor.
  3. Open spatialos.UnityWorker.worker.json in a text editor.
  4. If either of the above files have the line "generated_build_scripts_type" : "unity", automatically generated build scripts are turned on.

Next, check if the following three files already exist in the workers/unity folder of your SpatialOS project:

  • spatialos_worker_packages.json

Do you see all three of those files?

  • YES, I see all three of those files:

    • Remove the line "generated_build_scripts_type" : "unity" from BOTH of the build scripts (spatialos.UnityClient.worker.json and spatialos.UnityWorker.worker.json) as described above.

      This will prevent them from being over-written each time you build.

  • NO, I don’t see any of those files:

    1. Run spatial worker build once
    2. The files should now be generated.
    3. Remove the line "generated_build_scripts_type" : "unity" from BOTH of the build scripts i.e. spatialos.UnityClient.worker.json and spatialos.UnityWorker.worker.json as described above.

      This will prevent them from being over-written each time you build.

1. Modify your UnityClient build scripts

Add an additional build step to your Unity worker’s build configuration:

  1. Locate the workers/unity folder of your SpatialOS project.
  2. Open in a text editor.
  3. By default, you will have a task named “Codegen” with several steps, e.g., “Dependencies”, “C# standard library”, “C#”, etc.
  4. Go to the last step, which should be “Compile generated scripts”.
  5. Add a new step with the following content:

      "name": "Compile serializers for generated schemas",
      "description": "The restrictions on iOS prevent runtime code-generation of schema serializers. Precompile these serializers into a separate DLL that can be included for iOS compatibility.",
      "arguments": [
  6. You can also download an example JSON file.

2. Modify your worker packages

Add an additional worker package to your Unity worker’s worker packages JSON file:

  1. Locate the workers/unity folder of your SpatialOS project.
  2. Open spatialos_worker_packages.json in a text editor.
  3. By default, you would have several targets specified, each with a “path”, “type”, and a list of “packages”.
  4. Add three new targets by using the following content:

      "path": "Assets/Improbable/Sdk/Editor/Addons",
      "type": "unity",
      "packages": [
          "name": "Improbable.Unity.EditorAddOn.iOSBuildTools"
      "path": "Assets/Plugins/Improbable/darwin_ios-arm_dll",
      "type": "worker_sdk",
      "packages": [
          "name": "core-dynamic-arm-ios"
      "path": "Assets/Plugins/Improbable/darwin_ios-x86_64_dll",
      "type": "worker_sdk",
      "packages": [
          "name": "core-dynamic-x86_64-ios"
  5. You can also download an example JSON file.

3. Build your project

To apply the changes from the previous steps, build your project:

  1. In the terminal, build your project by running spatial worker build.
  2. Wait until the build process completes successfully and without any errors.
  3. Navigate to the folder workers/unity/Assets/Improbable/Sdk.
  4. You should see three sub-folders, Dll, Editor, and Src.
  5. In the Dll sub-folder, verify that the file Generated.Code.Serializer.dll is present.
  6. In the Editor sub-folder, verify that Addons/iOSBuildTools is present.

4. Modify your Unity project

Open your project in Unity. You’ll need to make the following changes to prepare the application for iOS build targets.

Add/modify the linker configuration

As Unity automatically strips out code and assemblies for iOS workers, it is important to add a linker configuration link.xml; it prevents some code, for example Protobuf serialization/deserialization method calls, from being stripped out by Unity.

For more information about iOS Worker optimizations and how to customize the linker configuration, refer to the Unity Documentation

  1. In Unity, add a file called link.xml into the Assets folder, if not already present.
  2. The contents of this file should contain the following:

       <assembly fullname="Generated.Code"                  preserve="all"></assembly>
       <assembly fullname="Generated.Code.Serializer"       preserve="all"></assembly>
       <assembly fullname="Improbable.WorkerSdkCsharp"      preserve="all"></assembly>
       <assembly fullname="protobuf-net"                    preserve="all"></assembly>
  3. You can also download this link.xml.

Modify the Bootstrap.cs game object

  1. in Unity, open the ClientScene or UnityClient scene found in the Assets folder of the project navigator.

    Open the Client Scene within Unity

  2. Click on the GameEntry game object in the scene hierarchy.

  3. Open the Bootstrap.cs MonoBehaviour script by double clicking on the script in the Inspector.

  4. By default, you will see the line:


    Delete and replace it with the following code snippet:

    List<string> commandLineArguments = null;
    #if UNITY_IOS
        // Set to the name of your SpatialOS project here.
        // This should match the project name as specified in spatialos.json
        const string APP_NAME = "<insert_your_project_name_here>";
        commandLineArguments = new List<string>(System.Environment.GetCommandLineArgs());
        commandLineArguments.AddRange(new List<string>()
            "+" + CommandLineConfigNames.AppName, APP_NAME
        Improbable.Worker.ProtobufTypeModel.Serializer = new Generated.Code.Serializer();
    SpatialOS.ApplyConfiguration(Configuration, commandLineArguments);
  5. IMPORTANT: Make sure to set the APP_NAME constant to your project name. This should match the project name as specified in spatialos.json.

  6. In the Bootstrap (Script) panel of the Inspector:

    • Click to expand Configuration -> Debugging.

      • For Infra Service URL:

        • If testing locally (spatial local launch), set to:

        • If testing against a deployment (spatial cloud launch), set to:

    • Click to expand Configuration -> SpatialOS Application.

      • For Assembly Name:
        • If testing locally (spatial local launch), set to: local_assembly
        • If testing against a deployment , leave it blank and not set.
      • For Login Token:
        • If testing locally (spatial local launch)), leave it blank.
        • If testing against a deployment, set it to a valid login token.
    • This image highlights the key settings required on your Bootstrap game object:

      Bootstrap Settings

5. Build the iOS Client Worker

This section outlines several additional modifications required to configure Unity correctly for SpatialOS and iOS.

Modify the iOS Worker Build Settings

The following build settings are recommended for compatibility with SpatialOS.

  1. Within Unity, access the build settings via: File -> Build Settings...

    Accessing the Unity Build Settings menu

  2. Under Platform, select iOS such that it is highlighted.

    Unity Build Settings

  3. Click on Player Settings.... This should show the Player Settings in the Inspector.

    • Click the icon to make sure that you are in the Settings for iOS tab:

      Player Settings Tab

    • Expand the Other Settings section:

      Player Settings: Other Settings Section

  4. Configure Other Settings with the following settings:

    • Configuration:
      • Scripting Backend: IL2CPP
      • Target SDK: Device SDK or Simulator SDK
      • Target minimum iOS Version: 10.2 or higher
      • Allow downloads over HTTP (nonsecure): Checked
      • Architecture: Universal (Device) or x86_64 (Simulator)
      • Scripting Define Symbols: CROSS_PLATFORM_INPUT;MOBILE_INPUT
    • Optimization
      • API Compatibility Level: .NET 2.0
      • Strip Engine Code: Unchecked
      • Script Call Optimization: Slow and safe
    • When you’re finished, your settings should look like this:

      Player Settings: Other Settings Example

Building the iOS Worker

  1. Return to the Build Settings panel:

    Player Settings: Other Settings Example

  2. (Optional) It is useful to set Run in Xcode as to Debug and to check Development Build. This will enable full stack traces to be visible when running from Xcode.

  3. Click Build.

  4. When the dialog prompts you to choose a location to save the project:

    • Navigate to workers/unity/build/worker/

      Hint: Click on the little arrow next to Save As to expand the panel to enable you to browse.

    • Create a folder called UnityClient@iOS, if it doesn’t already exist.

    • Click to select and highlight the UnityClient@iOS folder

    • Under Save As:, enter the name UnityClient@iOS.

    • Click Save.

    Note: The following image should resemble what you see on your screen. By making sure that the UnityClient@iOS folder is selected (blue), the generated Xcode project will be placed in a folder within the UnityClient@iOS folder.

    That is, your Xcode project file will be located in workers/unity/build/worker/UnityClient@iOS/UnityClient@iOS/Unity-iPhone.xcodeproj. The repeated folders are intentional! This will help maintain the same conventions and structure that standalone Unity workers have. Player Settings: Other Settings Example

  5. (Optional) Having done the above, you can now also specify iOS as a build target in your player-build-config.xml file. This will automatically build an iOS worker with the last saved build settings you have in Unity.

6. Update Xcode Build Settings

Once Unity has completed building the iOS worker, you will need to use Xcode to build and run the application on your iOS device or simulator. There are several settings to configure in the generated Xcode project. You have two options to make these changes:

  • Option 1: Use the Improbable->iOS->Update Xcode Build Settings menu in Unity:

    Player Settings: Other Settings Example

    This is the recommended approach. After doing so, you may then skip straight to Step 7: Codesign libCoreSdkDll.dylib.

  • Option 2: Follow the instructions outlined in the rest of this section.

Modify the Xcode project settings

Reminder: If you chose Option 1 above, you may skip this section and go straight to Step 7: Codesign libCoreSdkDll.dylib.

  1. Open the Xcode project located in: workers/unity/build/worker/UnityClient@iOS/UnityClient@iOS/Unity-iPhone.xcodeproj
  2. In the Project Navigator located on the left panel of Xcode, click on Unity-iPhone:

    Player Settings: Other Settings Example

  3. On the main pane of Xcode, click on Unity-iPhone listed under Targets(not Project!)

    Player Settings: Other Settings Example

  4. Click on the Build Settings tab.

    Make sure that both All and Combined tab settings are active. Then, make the following changes:

    Player Settings: Other Settings Example

    • Architectures
      • Architectures: x86_64 (Simulator) OR armv7,armv7s,arm64 (Device).
      • Base SDK: Change to Latest iOS from the dropdown menu (e.g., Latest iOS (iOS 10.2)).
      • Valid Architectures: x86_64 (Simulator) OR armv7,armv7s,arm64 (Device).
    • Linking
      • Runpath Search Paths: Add @executable_path.
    • Search Paths
      • Library Search Paths: Remove all double quotes from the entries listed there. e.g., $(SRCROOT)/Libraries should be just $(SRCROOT)/Libraries
      • Set to NO

Hint: Use the search bar to help find these settings.

Player Settings: Other Settings Example

Add libCoreSdkDll.dylib to the project

  1. Locate the appropriate platform version of the libCoreSdkDll.dylib in your project.

    • For iOS Simulators, locate it in workers/unity/Assets/Plugins/Improbable/darwin_ios-x86_64-dll/.
    • For iOS Devices, locate it in workers/unity/Assets/Plugins/Improbable/darwin_ios-arm-dll/.
  2. Copy the selected libCoreSdkDll.dylib into the folder: unity/build/worker/UnityClient@iOS/UnityClient@iOS/Data.

    You can do this also by drag-and-dropping the file into the Data folder in the Xcode project navigator. The image below shows how your project and file system should look:

    Player Settings: Other Settings Example

7. Codesign libCoreSdkDll.dylib

Codesign the libCoreSdkDll.dylib in your project using your Apple Certificates. This can be done by running the following command in the terminal:

codesign -s "iPhone Developer" <path_to_project>/workers/unity/build/worker/UnityClient@iOS/UnityClient@iOS/Data/libCoreSdkDll.dylib

8. Build and run Xcode project

  1. In Xcode, start building your project using the Product->Build menu or by using CMD+B.
  2. If you observe build errors related to Unknown type names (for example, OrConstraint_t1672328221), this is due to a bug in Unity’s IL2CPP code generation.

    • To fix these issues manually, and learn more about what causes them, refer to our Troubleshooting guide.
    • To fix these issues automatically, use this bash script:

      1. Download the script:
      2. Place it in your <path_to_your_project>/workers/unity/ directory.
      3. Run it from the <path_to_your_project/workers/unity directory.

        $ sh
  3. Run the project from Xcode by using the Product->Run menu, or using CMD+R, or pressing the play button.

    Note: As with all client workers, make sure that your server is running, either locally (spatial local launch) or from a deployment (spatial cloud launch).

If successful, Xcode will complete the build and begin running the application on your iOS device or iOS Simulator. BlankProject running on the iOS Simulator

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