title: cocos2d iphone game move to ipad
body: <p>i want to make my game universal. but when i try it on ipad, my background layer only covers 1/4 of the screen, but the sprites can go the entire screen. also the sizes of sprites are too small, didn't scale up. 
  when i see the apple doc, it says i have to "if else" to detect device every time use coordinate. but there are just so much code to be modified. 
  so is there any way to solve this? like just change in one place? </p>