iPhone - a question about drawRect -

suppose instead uiview subclass uiimageview , assign background image it, in

uiimageview *myimageview = [[uiimageview alloc] initwithimage: //... bla bla 

and implement drawrect method , use draw stuff on image.

my question is:

1. will stuff being drawn on image or in kind of "layer" totally independent?
2. if later true, how access "layer"?

thanks

if override drawrect, stuff drawn on image itself. every uiimage backed calayer, you're drawing onto that. access with

[image layer];