p5

这段搞不太定……

如果你用 `CGRectInset` 作为缩放矩形的快捷方法，一般通用的做法是嵌套调用`CGRectOffset`，把`CGRectInset`的返回值作为`CGRectOffset`的参数。 as a convenience function for resizing a rectangle, it is common to chain this with `CGRectOffset` by passing the result of `CGRectInset` as the `rect` argument in `CGRectOffset`.