Assume someone changed the font of the label, that you stored the new font and the related flag, and now you want LayoutManager to invoke the validation phase again.
假设某人更改了标签的字体，然后您存储了新的字体和相关标记，现在您需要让Layout Manager再次调用验证阶段。
When you change a font, you can create a new UITextField at the same time. Or, you can store the new font context and a flag indicating that fonts have changed.
在更改字体时，您可以同时创建一个新的UITextField，或者存储一个新的字体上下文和一个表明字体已经更改的标记。
Simply check whether the flag indicating a change in font status has changed and then create the corresponding UITextField at that time.
检查表明字体状态变更的标记是否改变，然后创建一个对应的UITextField。
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