括弧里面是对应的半径大小

App Store (Retina) -> 1024px (160px)
iTunes Artwork Icon -> 512px (90px)
App Icon (iPhone5s) -> 120px (22px)
App Icon (iPhone4s) -> 114px (20px)
App Icon (iPad) -> 72px (12px)
App Icon (iPhone 3G/3GS) -> 57px (10px)
Spotlight/Settings Icon (iPhone4) -> 58px (10px)
Spotlight/Settings Icon (iPhone 3G / 3GS / iPad) -> 29px (9px)