关于UGUI RectTransform的几个参数的获取和修改（待补充）

1.改变RectTransform的top
GetComponent().offsetMax = new Vector2(GetComponent().offsetMax.x, top);
2.改变RectTransform的bottom
GetComponent().offsetMin = new Vector2(GetComponent().offsetMin.x, bottom);
3.改变RectTransform的width，height
GetComponent().sizeDelta = new Vector2(width, height);
4.改变RectTransform的pos
GetComponent().anchoredPosition3D = new Vector3(posx,posy,posz);
GetComponent().anchoredPosition = new Vector2(posx,posy);