App Icons on iPad and iPhone

 

Latest:

http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/mobilehig/IconsImages/IconsImages.html 

 

App Icons on iPad and iPhone

http://developer.apple.com/library/ios/#qa/qa1686/_index.html 

 

This link is most help full  

http://www.idev101.com/code/User_Interface/sizes.html

Apple iphone Interface GuideLines

https://developer.apple.com/library/ios/#documentation/userexperience/conceptual/mobilehig/IconsImages/IconsImages.html

https://developer.apple.com/library/ios/#DOCUMENTATION/UserExperience/Conceptual/MobileHIG/UIElementGuidelines/UIElementGuidelines.html