With iPhone 4.0 SDK, all graphics/images are automatically scaled (including coordinates) according to the device screen resolution. All we have to do is provide two versions of each image used in our application – one to suit for the retina display, other one suit to normal resolution. All images that needs to be rendered for retina display must have a “@2x” in the filename (just before the file extension). If the device uses retina display, it will automatically load the @2x file, otherwise it will load the normal file and scale it up.