Unity can not access StreamingAssets on IOS

Now i’m working on a project which created by others. I need access image files stored in StreamingAssets folder. This is my C# code below:

IEnumerator Start () {
		_image = gameObject.GetComponent <RawImage>();

		string url = "file://" + System.IO.Path.Combine (Application.streamingAssetsPath, name);
		WWW www = new WWW(url);
		yield return www;

		if (www.error == null)
		{
			_image.texture = www.texture;
		}
		else 
		{
			Debug.Log ("[test] error : " + www.error);
		}
	}

I can totally make sure the file is right there. And it’s working perfect when i run on Unity Editor. But it shows “Unsupported URL” after i build as ios and run at my ios device.

I am confused for this question for a long time. So I decide to do a test by creating a totally new project and add a new scene, a new script, a png image. It’s working perfect when i run on iPhone after build it.

And now i do not know how to find the source of this question. Hope someone can help me. Thanks in advance.

You do not need to add “file://” prefix in url .