如何判断ios设备是否是高清屏幕

if([[[UIDevice currentDevice] systemVersion] floatValue] >= 3.2f)
            {
                CGRect winRect = [[UIScreen mainScreen] bounds];
                CCLOG("winRect w = %f, h = %f", winRect.size.width, winRect.size.height);
                CGSize winSize = [[UIScreen mainScreen] currentMode].size;
                CCLOG("currentModeSize w %f  h%f", winSize.width, winSize.height);
                bool isRetina =
                [UIScreen instancesRespondToSelector:@selector(currentMode)] ?
                CGSizeEqualToSize(CGSizeMake(winRect.size.width*2, winRect.size.height*2), winSize)
                ||CGSizeEqualToSize(CGSizeMake(winRect.size.height*2, winRect.size.width*2), winSize)
                : FALSE;
            }

//判断设备是否是高清设备