如果必须向多个架构中添加对象，由于必须不断更改默认架构，此方法无效。

This approach is inefficient if you must add objects to several schemas because you must keep changing the default schema.

youdao

公开此方法以便派生元素类可以对其自身可能的无效布局状态进行进一步的检查。

It is exposed so that derived element classes can make further checks on their own possibly invalid layout state.

youdao