Does iOS SDK provides an easy way to check if the currentDevice has an high-resolution display (retina) ?
The best way I've found to do it now is :
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] == YES && [[UIScreen mainScreen] scale] == 2.00) {
// RETINA DISPLAY
}
In order to detect the Retina display reliably on all iOS devices, you need to check if the device is running iOS4+ and if the [UIScreen mainScreen].scale
property is equal to 2.0. You CANNOT assume a device is running iOS4+ if the scale
property exists, as the iPad 3.2 also contains this property.
On an iPad running iOS3.2, scale will return 1.0 in 1x mode, and 2.0 in 2x mode -- even though we know that device does not contain a Retina display. Apple changed this behavior in iOS4.2 for the iPad: it returns 1.0 in both 1x and 2x modes. You can test this yourself in the simulator.
I test for the -displayLinkWithTarget:selector:
method on the main screen which exists in iOS4.x but not iOS3.2, and then check the screen's scale:
if ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] &&
([UIScreen mainScreen].scale == 2.0)) {
// Retina display
} else {
// non-Retina display
}