How to capture image merged by the camera ouput and its cameraOverlay in iphone

I want to capture the the image of camera taken, and this 开发者_Python百科image should come with its camera overlay image, how to do that?

And It seems that UIGetScreenImage() could not pass the appstore review.

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use AVCaptureSession and related classes in the AV Foundation Framework

see this official thread in Apple Developer Forums: UIGetScreenImage() Thread