Simulator iPhone Retina has wrong screen resolution

Question

I'm trying to write a Universal Application. The display should be slightly different for different screen resolutions. But when I code like this:

- (void)viewDidLoad {
    SCREEN_WIDTH=[[UIScreen mainScreen] applicationFrame].size.width;
    SCREEN_HEIGHT=[[UIScreen mainScreen] applicationFrame].size.height;
    NSLog(@"w:%f h:%f",SCREEN_WIDTH,SCREEN_HEIGHT);
...
}

I get output: w:320.000000 h:480.000000 even when the simulator is set to
Hardware->Device->iPhone (Retina)
Furthermore, images with this resolution display as full-screen images in the simulator.
I understand I should be getting w:640.000000 h:960.000000.
Is it like this for anyone else? And any ideas why/how to fix? See the related thread: here

Answer 1

UIScreen will always report the resolution of a Retina Display device as that of a non-Retina Display device. This allows old code to run transparently on such screens. However, UIScreen exposes a scale property which, when combined with the bounds of the screen, can be used to determine the physical pixel resolution of a device:

CGSize PhysicalPixelSizeOfScreen(UIScreen *s) {
    CGSize result = s.bounds.size;

    if ([s respondsToSelector: @selector(scale)]) {
        CGFloat scale = s.scale;
        result = CGSizeMake(result.width * scale, result.height * scale);
    }

    return result;
}

The resulting value on an iPhone 4 would be { 640.0, 960.0 }.