iPhone SDK System Provided Buttons and Icons

Where can the System-Provided Buttons and Icons mentioned in the following link to the iPhone Developer Human Interface Guidelines be found in the SDK? http://developer.apple.com/iphone/library/documentation/UserExperience/Conceptual/MobileHIG/SystemProvided/SystemProvided.html

I expected them to sho开发者_JAVA百科w up in Interface Builder somewhere, but I haven't been able to locate them.

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Apple has moved the link again, for iOS 7.

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

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Reading that link pointed me to this page¹, which under the appearance heading (as directed) I found the following quote:

In addition to custom buttons, you can configure bar button items using several standard images and titles. When a bar button item is selected, the Identifier field of the Attributes inspector lists the type of the button. Choosing a type other than Custom lets you create buttons representing standard system actions.

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¹ The original resource has been 302ed by Apple since this answer was written, thus the link to an archived copy.