Knowing device type -- Retina/non-Retina [duplicate]

Question

Possible Duplicate:
Detect Retina Display

How can we know if a device has a retina display or not from objective C code?

Answer 1

if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]
    && [[UIScreen mainScreen] scale] >= 2.0) {
    // Retina
} else {
    // Not Retina
}

Answer 2

You can check the scale property on [UIScreen mainScreen] if it is 2.0 you are running on retina, if it is 1.0 you are not. You can also get the scale from the current CoreGraphics Context.