Standard blue white buttons for iPhone

The default rounded rect button for the iPhone does not look as good as a lot of common apps that have the blue background, white background, red background, thicker 开发者_Go百科borders, etc. Is there documentation on what size for the radius of the rounded rect, or which images to use, where to get the images, etc? Thanks.

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According to Apple the size of a button should be 44 x 44 so that the user can easily use the buttons with a finger tap.

EDIT : Additionally go through the iOS Human Interface Guidelines document linked below (specifically the Rounded Rectangle Button part)

http://developer.apple.com/library/iOS/#documentation/UserExperience/Conceptual/MobileHIG/UIElementGuidelines/UIElementGuidelines.html