How to differentiate between iphone4 and iphone 3

Question

I am trying to build a game for the iphone using cocos2d engine. I wanted to know how can I tell a difference whether the user is using iphone 4 or iphone 3 as I wanted to l

Answer 1

Checking the scale property is not sufficient, as on iPad 3.2 in 2x mode, the scale property exists and will return 2.0, but we know that device does NOT have a Retina display.

I've created at category on UIScreen to do this. For a more detailed explanation, see my answer to Detect Retina Display. Here's the code:

@interface UIScreen(ZBScreenRetinaAdditions)

// Returns YES if this is a Retina display.
- (BOOL)zb_isRetina;

@end

@implementation UIScreen(ZBScreenRetinaAdditions)

- (BOOL)zb_isRetina {
  return [self respondsToSelector:@selector(displayLinkWithTarget:selector:)] && (self.scale == 2.0);
}

@end

Usage example:

if ([UIScreen mainScreen] zb_isRetina) {
  // Retina display
}