axmol/cocos2dx/platform/ios/CCDevice.mm

#include "CCDevice.h"
#import <UIKit/UIKit.h>

NS_CC_BEGIN

int CCDevice::getDPI()
{
    static int dpi = -1;

    if (dpi == -1)
    {
        float scale = 1.0f;
        
        if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
            scale = [[UIScreen mainScreen] scale];
        }
        
        if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
            dpi = 132 * scale;
        } else if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
            dpi = 163 * scale;
        } else {
            dpi = 160 * scale;
        }
    }
    return dpi;
}

NS_CC_END