Run Unity iOS app behind control center

iOSPostProcessor.cs

// Belongs in an Assets/**/Editor folder

public class iOSPostProcessor
    {
        /// <summary>
        /// Post processor to automate skipping the checkbox on testflight for encryption compliance.
        /// </summary>
        [PostProcessBuild(-999)]
        public static void OnPostProcessBuildRunInBackground(BuildTarget buildTarget, string path)
        {
            if (buildTarget != BuildTarget.iOS)
            {
                return;
            }

            string filePath = Path.Combine(path, "Classes", "UnityAppController.mm");
            string content = File.ReadAllText(filePath);

            // Check if this mod has already been applied -> if we have "append" the build.
            Regex regex = new Regex("applicationDidEnterBackground\\(\\).+?}", RegexOptions.Singleline);
            Match match = regex.Match(content);

            if (!match.Success)
            {
                Debug.LogError("Failed to parse UnityAppController.mm");
                return;
            }

            int numberOfLinesInMethod = match.Value.Split("\n").Length;

            if (numberOfLinesInMethod > 6)
            {
                Debug.Log("Skipped modification to UnityAppController.mm as applicationDidEnterBackground() had more content than expected.");
                return;
            }

            content = content
                .Replace("applicationWillResignActive", "###temp###")
                .Replace("applicationDidEnterBackground", "applicationWillResignActive")
                .Replace("###temp###", "applicationDidEnterBackground");

            File.WriteAllText(filePath, content);
            Debug.Log("Moved iOS pause functionality from applicationWillResignActive to applicationDidEnterBackground.");
        }
    }