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Game Center Login Setup Log #1

Note

This setup was done with:

Unity Version 2021.3.32f1
Authentication Package Version 2.7.2

Follow the Unity Get Started Documentation:
1. Sign up for Unity Gaming Services. Make sure you lauch the Authentication Service for your app. Sign up for the Apple Game Center identity provider and MAKE SURE THE STATUS ON THE PROVIDER IS ENABLED!
2. Link your project to the service within the editor by going to Edit > Project Settings, clicking the Services row. I made a project within the Unity Gaming Services website so i just linked the existing project.
3. Install the SDK by going to Window > Package Manager. Select the Unity Registry dropdown and select the Authentication package. Make sure it’s version is greater than or equal to 2.4.0. Otherwise you will need to upgrade your unity version to get access to a higher package version.
4. In your unity project, make sure when the app starts to run you initialize the Unity Services SDK. by calling await UnityServices.InitializeAsync();. See the UGS Manual for the full code snippet.
Follow the Unity Apple Game Center Documentation
1. Install the Apple Core & Game Kit Unity Plugins
2. If you want to include these packages in your version control system, I suggest moving the generated .tgz files within the Unity Project’s Packages directory. Then when you add the packages using the package manager’s Add Package From Tarball method, it will store the relative paths to those files.
3. Note I made the apple core package a custom package so that I could modify some of the c# files to make game center work. To make a package custom in unity simply navigate to your Unity Project directory, go to Library / Package Cache, identify the package of interest (has a similar name), and drag it into the Packages folder. For more information see How can I modify built-in packages?
4. Next add Apple Game Center as an ID provider for Unity by going to Unity Gaming Services. There select your project, scroll down to services and select Player Authentication. Click the Launch button and add Apple Game Center as a provider. Make sure to add the bundle identifier of your app (you should see it on Xcode under the General tab in the Identity section).
5. Next include the AppleGameCenterExampleScript provided on Apple Game Center Documentation page and make sure to add and call the SignInWithAppleGameCenterAsync function when your app loads.
Follow Apple’s Guide to Enabling Game Center
1. Go to the Signing and Capabilities tab in Xcode, Click the + Capability button and double click GameCenter
For some reason Apple will not recognize Game Center with your app unless you add 1 leaderboard to it. (See this forum post for more information)
1. See this guide to Configure leaderboards in App Store Connect
2. For me, on App Store Connect:
  - I selected my app
  - I selected the Services tab
  - I clicked the Game Center Row
  - I scrolled down to Leaderboards and I clicked the blue plus button to add a new leaderboard.
When I tried to build the app to IOS, I encountered the following build errors:

Error

Building for ‘iOS’, but linking in dylib (/Users/jeffreyspitz/UnityProjects/TunnelTwisterV3/Builds/iOSBuild/Frameworks/com.apple.unityplugin.core/Plugins/tvOS/AppleCoreNative.framework/AppleCoreNative) built for ‘tvOS’

My solution for this this is to do the following:
1. Make both the apple core package a and apple gamekit package custom (If you have not done so already). To start in your unity project files to Library / Package Cache, identify the package of interest (has a similar name), and drag it into the Packages folder. For more information see How can I modify built-in packages?
2. Inside the UnityEditor in the project window navigate to Packages > Apple.Core > Plugins > tvOS. Select The AppleCoreNative plugin file and under its import settings in the inspector select Editor. This way we don’t have it building to ios.
3. Netxt we repeat the same process for the GameKit package. Inside the UnityEditor in the project window navigate to Packages > Apple.GameKit > Plugins > tvOS. Select The AppleCoreNative plugin file and under its import settings in the inspector select Editor. This way we don’t have it building to ios.
When I tried to run the app to IOS, I also encountered the following error:

Error

dyld[20195]: missing symbol called

And this error occured when encountering the function GKLocalPlayer_GetLocal (when calling GKLocalPlayer.Local.FetchItems() from the gamekit package. It turns out there was a forum post with other people facing the same issue. There was a Google Doc posted on Oct 17 2023 by a member of Unity Technologies about a workaround for the issue. After looking at the document I did the following to fix the bug:
1. I cloned the apple unity plugins repo outside my unity project
2. I did not edit the unity plugins repo and simply built all packages using the standard python3 build.py command.
3. I dragged the tarball files into my unity project under the Packages Directory.
4. I added the tarball files of core and gamekit through the package manager window and then I repeated the step above where i made the packages custom and targeted the tvOS plugins to the editor.
5. I completed the step below where I added a code fix to AppleFrameworkUtility.cs script’s “GetPluginLibraryPathForBuildTarget” method
6. I Modified the GKLocalPlayer script as outlined in the Google Doc.
7. I checked to make sure GameCenter was enabled as part of signing and capabilities in XCode.

If after you build your app to your iphone and you encounter errors like package files not being found when trying to connect to game center try out the following:

I found this post on the forums helpful: Unity Apple plugin Issue.
Essentially go to AppleFrameworkUtility.cs script’s “GetPluginLibraryPathForBuildTarget” method and add the following lines of code. (Github reference)

// try without the .framework, Unity.2022 AssetDatabase.FindAssets fails with ".frameworks"
if( libraryName.EndsWith(".framework") )
{
    string libraryNameWithoutFramework = libraryName.Substring( 0, libraryName.LastIndexOf(".framework") );
    results = AssetDatabase.FindAssets(libraryNameWithoutFramework);
    foreach (string currGUID in results)
    {
        string libraryPath = AssetDatabase.GUIDToAssetPath(currGUID);
        string[] folders = libraryPath.Split('/');
        if (Array.IndexOf(folders, platformString) > -1)
        {
            return libraryPath;
        }
    }

}

If after you are still encountering errors at the GKLocalPlayer.Local.FetchItems stage (even when the authentication step works) it could be because of an issue with GameCenter on your iOS device (reddit thread). To fix it simply sign out of GameCenter on your device and sign back in.
Once we got Game Center authentication running without crashes, we ran into 2 errors when trying to display the GameCenter dashboard when calling the following lines of code:
```
var gameCenter = GKGameCenterViewController.Init(GKGameCenterViewController.GKGameCenterViewControllerState.Dashboard);
await gameCenter.Present();
```
The first error was the following:

Error

This application is modifying the autolayout engine from a background thread after the engine was accessed from the main thread. This can lead to engine corruption and weird crashes.

This message was raised because we tried calling the asynchronous code above from the main thread using Task.Run(): Task.Run(() => GameCenterAsyncMethod()).Wait();. The solution was to make our GameCenterAsyncMethod have a return type of void instead of Task: private async void GameCenterAsyncMethod(). This method was called when a unity event was raised so we just passed the function into the AddListener method: gameEvent.AddListener(GameCenterAsyncMethod)

The second error was the following:

Error

Default constructor not found for type Apple.GameKit.GKGameCenterViewController

To resolve this issue, inside my Assets folder i created a folder called iOS and added a file called link.xml to it. The contents of it were as follows:
```
<linker>
    <assembly fullname="Apple.Core" ignoreIfMissing="1" preserve="all"/>
    <assembly fullname="Apple.GameKit" ignoreIfMissing="1" preserve="all"/>
</linker>
```
The attribute preserve="all" to preserve all members of the Apple.Core and Apple.GameKit assemblies so that they aren’t accidentally discarded like the constructor for Apple.GameKit.GKGameCenterViewController. By placing this file inside Assets/iOS this only affects the iOS build of the project.
When opening my unity project on my laptop running windows 10, I encountered the following error:

Error

The type or namespace name ‘PlistDocument’ could not be found.

All i had to do to fix the error was go into AppleBuildStep.cs inside the Apple.Core package and change the using statement of UnityEditor.iOS.Xcode to:
```
#if UNITY_EDITOR_OSX || UNITY_EDITOR_WIN
using UnityEditor.iOS.Xcode;
#endif
```