Accessing iOS 6 new APIs for camera exposure and shutter speed

Question

On Apple\'s iOS 6.0 feature page, it used to say

Take advantage of the built-in camera’s advanced features. New APIs let you control focus, exposure,

Answer 1

As a follow-up to Michael Grinich's excellent information, I found that there is an order dependency on some of the calls in the private API. To use "manual" exposure controls, you have to enable them before you set the mode, like so:

#define AVCaptureExposureModeManual     3
NSError*    error = nil;
if ([captureDevice lockForConfiguration:&error]) {
    captureDevice.manualExposureSupportEnabled = YES;
    if ([captureDevice isExposureModeSupported:AVCaptureExposureModeManual]) {
        captureDevice.exposureMode = AVCaptureExposureModeManual;
        captureDevice.exposureGain = ...;
        captureDevice.exposureDuration = {...};
    }
    [captureDevice unlockForConfiguration];
}

All of this is demonstrated in iOS-ManualCamera.