图片路径必须是Assets\Resources目录下面的, 并且不能带扩展名
//E:\Assets\Resources\img\abc.jpg
string filePath = "img/abc";
var texture = Resources.Load<Texture2D>(filePath);
GameObject obj = new GameObject("newname", typeof(SpriteRenderer));
SpriteRenderer render = obj.GetComponent<SpriteRenderer>();
var sprite = Sprite.Create(texture, new Rect(0, 0, texture.width, texture.height), new Vector2(0.5f, 0.5f));
render.sprite = sprite;