Screen resolution iOS Devices and graphics

Question

Heyho,

Each iOS device has a different screen resolution and pixel density.

Why do I need to support non-retina and retina graphics only and dont make graphics for each different screensize (e.g. 4 graphics each for a iPad App)? How does Xcode adjusts graphics to these screens?

EDIT

Our designer says she has to make 4 graphics for each device (due to density and screensizes) and I need to explain to here, why a retina and a non-retina graphic are enough.

Answer 1

All iPad devices have a screen dimension of 1024x768 points (not pixels).

Retina devices have a scaling factor of 2, so you will need to create two sets of graphics, one for non-retina and one for retina; the difference being that the retina images are twice the size in each dimension (i.e. 4 times bigger overall).

So you don't need to worry about each iPad model; simply that it's retina or not.