Embossing Embossed iOS UIPickerViews

So, I can easily create a static embossed view by adding the shadow color and offset to the UILabel as described in several questions and answers on SO.

However, the main system of UIPickerViews (eg Clock-> Timer, Clock-> Alarm-> Edit) is not static! If you look closely, they will only be embossed during fitting. And half-dragging one of the labels from the selection bar actually makes half the embossed label and the other half doesn't, as shown in this picture:

Any ideas on how this is achieved?