iOS: Create one sideded dropshadow

Question

I have the below menu style layout that mimics facebook. I would like to have a dropshadow on the left side like below however the code I am using with layer shadows makes the a

Answer 1

I for myself would just add a UIView containing that shadow as a subview and reposition it as soon as the view on the right side is animated. (e.g. draw that shadow with layers or core graphics)