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