StreamingAssetsをプラットフォームごとに分ける

StreamingAssetsDynamicTest.cs

using UnityEditor.Build;
using UnityEditor;

public class StreamingAssetsDynamicTest : BuildPlayerProcessor
{
    public override void PrepareForBuild(BuildPlayerContext buildPlayerContext)
    {
        var buildTarget = buildPlayerContext.BuildPlayerOptions.target;

        switch (buildTarget) {
            case BuildTarget.StandaloneWindows:
                buildPlayerContext.AddAdditionalPathToStreamingAssets("AssetBundles/Windows");
                break;
            case BuildTarget.Android:
                buildPlayerContext.AddAdditionalPathToStreamingAssets("AssetBundles/Android");
                break;
            case BuildTarget.iOS:
                buildPlayerContext.AddAdditionalPathToStreamingAssets("AssetBundles/iOS");
                break;
        }
    }
}