I am working for a client to develop an iOS app both for iPhone and iPad including for retina displays.
The client is going to get the UX designs himself. We use the Apple's iOS Human Interface Design Guidelines to whoever is designing the UX for our apps.
In the article it explicitly mentions that:
____________________________________________________________________________
| | Size for iPad | Size for high-resolution iPad |
|_________________|________________________|_______________________________|
| Launch image | | |
| (required for | 768 x 1004 (portrait) | 1536 x 2008 (portrait) |
| all apps) | 1024 x 748 (landscape) | 2048 x 1496 (landscape) |
|_________________|________________________|_______________________________|
Does this mean that for each screen design (besides the launch screen) the designer has these canvas sizes as well?
Because, the screen size in iPad specs is 2048 x 1536 (portrait) and 1536 x 2048 (landscape). And for iPhone 4 the complete screen size 640 x 960 was used as canvas size!
UPDATE: Found reference to it here under section "Launch Images"