iPad/iPhone retina display image naming rule

iOS很聰明 ipad跟iphone的影像檔只要按照官方的naming rule
他就會幫你自動挑選合適的影像

Example:

For devices without retina:
ImageName.png - For iPhone/iPod
ImageName~ipad.png -- For iPad

For devices with retina display:
ImageName@2x.png - For iPhone/iPod
ImageName@2x~ipad.png -- For iPad

程式只需要寫

[UIImage imageNamed:@"ImageName.png"];

icon Size的部份

57 px, iPhone – Good ol』 classic.
114 px, Retina iPhone
72 px, iPad
144 px, Retina iPad
29 px, iPhone Settings/Spotlight, iPad Settings – Used in these table views. Minor, but still important!
58 px, iPhone 4 Settings/Spotlight/Notifications – That's right, you have to make both 57 and 58 px versions of your icon – d』oh! Good luck aligning this if there's a line running down the middle of the icon.
48 px, iPad Spotlight – Yup, the iPad uses a different size for Spotlight and Settings. Apple's docs actually say the icon is 50 px, but then there's this note: The final visual size of this icon is 48 x 48 pixels. iPhone OS trims 1 pixel from each side of your artwork and adds a drop shadow. Be sure to take this into account as you design your icon. So, leave extra room around your icon.
96 px, Retina iPad Spotlight. See note 7 above, and remember the edge will be trimmed by 2 px on each side.
22 x 29 px document icon, iPhone
44 x 58 px document icon, Retina iPhone
64 px document icon, iPad
320 px document icon, iPad
640 px document icon, Retina iPad
512 px, iTunes – Used in iTunes and in the App Store, where it's sized down to 175 px. Sadly, you can't provide the 175 px version directly.
1024 px, Retina iTunes

可以參考這篇
http://mrgan.tumblr.com/post/708404794/ios-app-icon-sizes

See also :

http://stackoverflow.com/questions/9611061/how-to-support-both-ipad-and-iphone-retina-graphics-in-universal-apps
http://developer.apple.com/library/ios/#documentation/2DDrawing/Conceptual/DrawingPrintingiOS/SupportingHiResScreens/SupportingHiResScreens.html#//apple_ref/doc/uid/TP40010156-CH15-SW8

FENDER TIMES