Taking screenshot of iphone device without using UIGetScreenImage() from private API

I just wanted开发者_JAVA百科 to ask whether there is a way to take the screen shot of iPhone device. I don't want to use the private API. I want to take the screen shot of entire screen, not just application. Is there a way to do it? please post it. Any help will be much appreciated.

Thanks in advance.

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Well you need to use Quartz functionality to achieve this