swift - Looking for an "Zoom"-effect event handler for UICollectionViewCell in tvOS -

i have in case of uicollectionviewcell zoom out (hover state).

i thought effect updates bounds of cell , i've overridden bound variable.

but didsetmethod triggered first time (original size) , not new size during zooming.

override var bounds: cgrect {     didset     {         // magic     } } 

what correct way catch kind of event?

i think transform property of view changes, not trigger bounds change, perhaps watch transform property or transform property of view's layer. problem layer transform change may not observe change there.