iPhone UIImagePickerController: show camera preview on top of openGl viewport

i've a question开发者_开发技巧 about UIImagePickerController class reference, in photo-camera mode.

I'm developing an OpenGl game. I should add to game photo-camera features: game should open a window (say for example 200x200 pixels, in the middle of screen), that display in real time a preview of photo-camera IN FRONT OF GL VIEWPORT. So photo-camera preview must be in a window of 200x200 in front of our Gl viewport that display game.

I've some questions: - main problem is that i've difficult to open UIImagePickerController window in front of our Gl viewport (normally UIImagePickerController window covers all iPhone screen);

• which is the better way to capture an image buffer periodically to perform some operations, like face detection (we have library to perform this on a bitmap image) ?

• iPhone can reject such approach? It's possible to have this approach with camera (camera preview window that partially overlap an openGl viewport) ?

• at the end, it's possible to avoid visualization of camera shutter? I'd like to initialize camera without opening sound and shutter visualization.

This is a screenshot: http://www.powerwolf.it/temp/UIImagePickerController.jpg

If you want to do something more custom than what Apple intended for the UIImagePickerController, you'll need to use the AV Foundation framework instead. The camera input can be ported to a layer or view. Here is an example that will get you half way there (it is intended for frame capture). You could modify it for face detection by taking sample images using a timer. As long as you use these public APIs, it'll be accepted in the app store. There are a bunch of augmented reality applications that use similar techniques.

http://developer.apple.com/library/ios/#qa/qa2010/qa1702.html