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Setting up MRTK on iOS

In this tutorial I walk through how I setup the open source Mixed Reality Toolkit (MRTK) the framework which drives the interactions on Hololens 2 on iOS. I'll be mostly following a couple guides from Microsoft on getting started but also throw in some notes on issues I hit during the setup process.

Getting started with MRTK

The Mixed Reality Toolkit (MRTK) is a cross-platform toolkit for building Mixed Reality experiences for Virtual Reality (VR) and Augmented Reality (AR). To get started with the Mixed Reality Toolkit, you will need: Get the latest MRTK Unity packages Import MRTK packages into your Unity project Switch your Unity project to the target platform Add MRTK to a new scene or new project Go to the MRTK release page.

https://microsoft.github.io/MixedRealityToolkit-Unity/Documentation/GettingStartedWithTheMRTK.html

How to configure MRTK for iOS and Android [Experimental]

Download and import the Microsoft.MixedReality.Toolkit.Providers.UnityAR package, from GitHub or NuGet Note After you import the the UnityAR package, you will see the following error: Assembly has reference to non-existent assembly 'Unity.XR.ARFoundation' (Assets/MixedRealityToolkit.Staging/UnityAR/Microsoft.MixedReality.Toolkit.Providers.UnityAR.asmdef) ". To resolve, install the correct version of ARFoundation listed below.

https://microsoft.github.io/MixedRealityToolkit-Unity/Documentation/CrossPlatform/UsingARFoundation.html

Install Unity

The first step to getting MRTK running is installing Unity and Visual Studio 2019. MRTK is supported on other platforms but it looks like Unity is the easiest way to get started with the framework.

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Unity versions 2019.1.x, 2019.2.x and 2018.4.x were supported when this article was written, however, I recommend installing 2018.4.x through Unity Hub because I was not able to get the UnityAR plugin running properly on Unity 2019.x.

Unity Hub Download Link: https://public-cdn.cloud.unity3d.com/hub/prod/UnityHubSetup.dmg

Installing MRTK Packages

Now that we have Unity installed, we need to install a few AR packages to set it up for MRTK. We first need to install the ARFoundation and ARKit XR packages. To do this, open the Package Manager on Unity, search for the package name and click install.

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Note: The ARFoundation package on Unity 2018.4.x is in preview. You need to enable preview packages on the Package Manager and install Version 1.5.0 Preview 6. This option is under Window > Package Manager > Advanced > Show Preview Packages

We can now install the custom MRTK packages. Go to the MRTK GitHub releases page and download the following packages from the latest release:

Microsoft.MixedRealityToolkit.Unity.Foundation

Microsoft.MixedReality.Toolkit.Providers.UnityAR

Microsoft.MixedRealityToolkit.Unity.Examples

Install the three packages by selecting the "Assets > Import Package > Custom Package" menu item and selecting each .unitypackage file

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Note: If you're using a Mac, uncheck the "Enable MSBuild for Unity" Checkbox in the default configuration when installing the MRTK package. It will keep prompting you to check this box, but click the ignore button to silence the alert. This caused lots of headaches in the setup process for me but it is a known issue and will likely be fixed soon.

Setting up the example scene

It's time to get a scene into our project! To make sure everything works, we'll setup the HandInteractionExamples demo that was shown with the Hololens 2 debut. Open the Assets/MixedRealityToolkit.Examples/Scenes/HandInteractionExamples scene using the project navigator pane at the bottom of Unity.

Next, we need to add the UnityAR Camera settings provider to the scene. Make a copy of the script by clicking the clone button as shown below.

Add the MixedRealityToolkit object to the scene from the "Mixed Reality Toolkit/Add to Scene and Configure" tab

Build Settings

Change the build target of the Unity project to iOS, this might regenerate the assets in the project.

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Note: Uncheck the "Strip Engine Code" option in Player Settings to prevent build errors in Xcode.