Can I set the scaleFactor of an UIView when I want my drawing code in -drawRect to not waste too much memory?

I am drawing something into -drawRect of an UIView, and in this case I really want a certain amount of pixels. With the retina display, my view has a scaleFactor of 2.0 and when I draw something that is supposed to be 10 pixels heigh, it's actually 20 heigh. Is it okay to set the scale factor back to 1.0 to get a 1:1 mapping between po开发者_高级运维ints and pixels?

The official documentation says it's ok.

See 'Accounting for Scale Factors in Core Animation Layers' in 'iOS Application Programming Guide' for details.

Wrong guide - try the section "Accounting for Scale Factors in Core Animation Layers", in "Drawing and Printing Guide for iOS"