Auto Focus and Auto Exposure in AVFoundation on Custom Camera Layer - ios

Question

What is the best way to create an accurate Auto Focus and Exposure for AVFoundation custom layer camera?, for example, currently my camera preview layer is square, I would like the camera focus and exposure to be specify to that frame bound. I need this in Swift 2 if possible, if not please write your answer I would be able to convert it myself.
Current Auto Focus and Exposure: But as you can see this will evaluate the entire view when focusing.
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
//Get Touch Point
let Point = touches.first!.locationInView(self.capture)
//Assign Auto Focus and Auto Exposour
if let device = currentCameraInput {
do {
try! device.lockForConfiguration()
if device.focusPointOfInterestSupported{
//Add Focus on Point
device.focusPointOfInterest = Point
device.focusMode = AVCaptureFocusMode.AutoFocus
}
if device.exposurePointOfInterestSupported{
//Add Exposure on Point
device.exposurePointOfInterest = Point
device.exposureMode = AVCaptureExposureMode.AutoExpose
}
device.unlockForConfiguration()
}
}
}
Camera Layer: Anything in the 1:1 ratio should be considered as focus and exposure point, and anything outside this bound would not even be considered as a touch event for camera focus.

Answer 1

public func captureDevicePointOfInterestForPoint(pointInLayer: CGPoint) -> CGPoint
will give you the point for the device to focus on based on the settings of your AVCaptureVideoPreviewLayer. See the docs.

Answer 2

Thanks to JLW here is how you do it in Swift 2. First, we need to setup Tap gesture you can do this programmatically or Storyboard.
//Add UITap Gesture Capture Frame for Focus and Exposure
let captureTapGesture: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "AutoFocusGesture:")
captureTapGesture.numberOfTapsRequired = 1
captureTapGesture.numberOfTouchesRequired = 1
self.captureFrame.addGestureRecognizer(captureTapGesture)
Create a function base on our selector in captureTapGesture.
/*=========================================
* FOCUS & EXPOSOUR
==========================================*/
var animateActivity: Bool!
internal func AutoFocusGesture(RecognizeGesture: UITapGestureRecognizer){
let touchPoint: CGPoint = RecognizeGesture.locationInView(self.captureFrame)
//GET PREVIEW LAYER POINT
let convertedPoint = self.previewLayer.captureDevicePointOfInterestForPoint(touchPoint)
//Assign Auto Focus and Auto Exposour
if let device = currentCameraInput {
do {
try! device.lockForConfiguration()
if device.focusPointOfInterestSupported{
//Add Focus on Point
device.focusPointOfInterest = convertedPoint
device.focusMode = AVCaptureFocusMode.AutoFocus
}
if device.exposurePointOfInterestSupported{
//Add Exposure on Point
device.exposurePointOfInterest = convertedPoint
device.exposureMode = AVCaptureExposureMode.AutoExpose
}
device.unlockForConfiguration()
}
}
}
Also, if you like to use your animation indicator, please use touchPoint at your touch of an event and assign it to your animated layer.
//Assign Indicator Position
touchIndicatorOutside.frame.origin.x = touchPoint.x - 10
touchIndicatorOutside.frame.origin.y = touchPoint.y - 10