/// <summary>下拉框改变事件</summary> public static void AddChange(this Dropdown drop, UnityAction <int> action) { drop.onValueChanged.AddListener(action); //修复Unity2019下拉框在不在Default层显示不出来的BUG drop.AddClick(() => { var list = drop.GetComponentsInChildren <Canvas>(); Canvas parent = drop.GetComponentInParent <Canvas>(); if (parent != null) { for (int i = 0; i < list.Length; i++) { list[i].sortingLayerID = parent.sortingLayerID; } } }); }