UnityでWebViewを動作させようとするとクラッシュが発生する

Question

macOS X 上のUnity2018.3.6f1でWebViewを実行しようと考え、プロジェクトを作成し、git(https://github.com/gree/unity-webview)より取得したzipより

dist/unity-webview.unitypackage

をプロジェクトにドロップして必要なソースを取得し、HierarcyにWebView用等のオブジェクトを作成し以下のようにソースを組んでオブジェクトに付与しました。

using UnityEngine;

public class SampleWebView : MonoBehaviour
{
    private string url = "http://www.google.com/";
    WebViewObject webViewObject;

    void Start()
    {
        webViewObject =
            (new GameObject("WebViewObject")).AddComponent<WebViewObject>();
        webViewObject.Init((msg) => {
            if (msg == "clicked")
            {
                webViewObject.SetVisibility(false);
            }
        });

        webViewObject.LoadURL(url);
        
        webViewObject.SetMargins(50, 100, 50, 50);
        
        webViewObject.SetVisibility(true);

        webViewObject.EvaluateJS(
            "window.addEventListener('load', function() {" +
            "	window.addEventListener('click', function() {" +
            "		Unity.call('clicked');" +
            "	}, false);" +
            "}, false);");

    }

    void OnGUI()
    {
        Rect textArea = new Rect(100, 0, 400, 100);
        url = GUI.TextArea(textArea, url);

        if (GUI.Button(new Rect(500, 0, 100, 100), "GO"))
        {
            webViewObject.LoadURL(url);
            webViewObject.SetVisibility(true);
        }
    }
}

しかし、毎回Unityでクラッシュが発生してしまいます。
ソースを辿ったところ、　webViewObject.SetVisibility(true);　でクラッシュは発生しており、エラーログを見てみると以下のようなクラッシュログが残っておりました

Reloading assemblies for play mode.
Begin MonoManager ReloadAssembly
Initializing Unity.PackageManager (PackageManager) v2018.3.6 for Unity v2018.3.6f1
Registering platform support modules:
Registered platform support modules in: 0.0540608s.
Native extension for Android target not found
Native extension for iOS target not found
Native extension for OSXStandalone target not found
Refreshing native plugins compatible for Editor in 2.58 ms, found 4 plugins.
Preloading 1 native plugins for Editor in 1.31 ms.
Mono: successfully reloaded assembly
- Completed reload, in  1.416 seconds
Platform modules already initialized, skipping
Load scene 'Temp/__Backupscenes/0.backup' time: 0.279816 ms 
Refreshing native plugins compatible for Editor in 0.49 ms, found 4 plugins.
Fallback handler could not load library /Applications/Unity/Hub/Editor/2018.3.6f1/Unity.app/Contents/Frameworks/Mono/lib/libAssets/Plugins/WebView.bundle/Contents/MacOS/WebView
Fallback handler could not load library /Applications/Unity/Hub/Editor/2018.3.6f1/Unity.app/Contents/Frameworks/Mono/lib/libAssets/Plugins/WebView.bundle/Contents/MacOS/WebView.dylib
Fallback handler could not load library /Applications/Unity/Hub/Editor/2018.3.6f1/Unity.app/Contents/Frameworks/Mono/lib/libAssets/Plugins/WebView.bundle/Contents/MacOS/WebView.so
Fallback handler could not load library /Applications/Unity/Hub/Editor/2018.3.6f1/Unity.app/Contents/Frameworks/Mono/lib/libAssets/Plugins/WebView.bundle/Contents/MacOS/WebView.bundle
Receiving unhandled NULL exception
Obtained 12 stack frames.
Thread 0x700014e99000 may have been prematurely finalized
#0  0x007fff50c9ac44 in glGetIntegerv
Thread 0x700014e99000 may have been prematurely finalized
#1  0x00000123c9c96c in -[CWebViewPlugin render]
Thread 0x700014e99000 may have been prematurely finalized
#2  0x00000123c9d185 in UnityRenderEvent
Thread 0x700014e99000 may have been prematurely finalized
#3  0x00000100fcb16f in GfxDevice::InsertCustomMarkerCallback(void (*)(int), int)
Thread 0x700014e99000 may have been prematurely finalized
#4  0x00000102a5d8a9 in GfxDeviceWorker::RunCommand(ThreadedStreamBuffer&)
Thread 0x700014e99000 may have been prematurely finalized
#5  0x0000010078f08c in GfxDeviceWorkerAutoreleasePoolProxy
Thread 0x700014e99000 may have been prematurely finalized
#6  0x00000102a654c0 in GfxDeviceWorker::RunExt(ThreadedStreamBuffer&)
Thread 0x700014e99000 may have been prematurely finalized
#7  0x00000102a5af51 in GfxDeviceWorker::RunGfxDeviceWorker(void*)
Thread 0x700014e99000 may have been prematurely finalized
#8  0x00000100e69542 in Thread::RunThreadWrapper(void*)
Thread 0x700014e99000 may have been prematurely finalized
#9  0x007fff6f546661 in _pthread_body
Thread 0x700014e99000 may have been prematurely finalized
#10 0x007fff6f54650d in _pthread_body
Thread 0x700014e99000 may have been prematurely finalized
#11 0x007fff6f545bf9 in thread_start
Launching bug reporter
（中略）
Assertion failed on expression: 'Thread::EqualsCurrentThreadID(Thread::mainThreadId)'
 
(Filename: /Users/builduser/buildslave/unity/build/Editor/Src/SceneInspector.cpp Line: 532

これはどのような事象、あるいは設定ミスが考えられますでしょうか？
よろしくお願いいたします。

Answer 1

urlをhttpsに変更したらどうなりますか？

iOSでhttp通信するにはApp Transport Securityの設定を変更する必要があります。