Is there any difference between iPad 2x mode and iPhone4 Retina display (for developer)?

Question

Graphics development for iPhone4 and old iPhones was changed in several ways:

1. The concept of point was introduced to replace pixel.
2. Methods of UIImage will load high resolution resource files with @2x in the file name.
3. Scale factor was added to UIScreen, UIView, UIImage, and CALayer classes.

So if we handle CGImage carefully, it's not hard to support the high resolution Retina display of iPhone4.

I have several questions about non-native iPad app in iPad 2x mode:

1. Could all the changes from old iPhone to iPhone4 (@2x resources auto loading, point concept, scale factor) be applied to iPad 2x mode.

2. The scale of app on iPad can be changed. How can I handle it?

Answer 1

Unfortunately, all of those content scale functions were added in 4.0, so I don't think there's any way to use the iOS4 stuff that you're asking for.

Answer 2

The iPad 2x mode is just a way to run iPhone-only apps on the iPad's larger screen. If you want to take advantage of iPad's larger screen, all you have to do is create a universal binary (i.e. one that contains views for both iPhone and iPad).