Add a shadow to a masked image

Question

Hi there,

I'm currently creating irregular images and I'd like to add a shadow to it programmatically :

1) load image (png file)

2) load mask (png file)

3) mask image with mask : output is an UIImage

4) add shadow to the irregular image (not squared nor circle) ...??

how do i do point 4 : should I
1) copy the current image

2) then change the alpha of the copy

3) combine original with its shadowed one ... ... If yes, How : combine 2 uiimage in one uiimageview ... ?

Thanks,

Tib.