AVFoundation tap to focus feedback rectangle

Question

I am developing an iphone application where I directly use AVFoundation to capture videos via the camera.

I\'ve implemented a feature to enable the tap to focus

Answer 1

Here's a basic Swift view that will show an animated focus square. Just add it to your camera view and hook it up to the focus callback from a tap gesture recognizer.

@objc func didTapToFocus(gesture: UITapGestureRecognizer) {
    let pointInViewCoordinates = gesture.location(in: gesture.view)
    let pointInCameraCoordinates = cameraView.videoPreviewLayer.captureDevicePointConverted(fromLayerPoint: pointInViewCoordinates)
    camera.focusOn(pointInCameraCoordinates: pointInCameraCoordinates)
    cameraView.showFocusBox(at: pointInViewCoordinates)
}

Focus view:

final class CameraFocusBoxView: UIView {

    // MARK: - Instantiation

    init() {
        super.init(frame: .zero)

        backgroundColor = .clear
        layer.addSublayer(focusBoxLayer)
    }

    // MARK: - API

    /// This zooms/fades in a focus square and blinks it a few times, then slowly fades it out
    func showBox(at point: CGPoint) {
        focusBoxLayer.removeAllAnimations()
        let scaleKey = "zoom in focus box"
        let fadeInKey = "fade in focus box"
        let pulseKey = "pulse focus box"
        let fadeOutKey = "fade out focus box"
        guard focusBoxLayer.animation(forKey: scaleKey) == nil,
              focusBoxLayer.animation(forKey: fadeInKey) == nil,
              focusBoxLayer.animation(forKey: pulseKey) == nil,
              focusBoxLayer.animation(forKey: fadeOutKey) == nil
            else { return }

        CATransaction.begin()
        CATransaction.setDisableActions(true)
        focusBoxLayer.position = point
        CATransaction.commit()

        let scale = CABasicAnimation(keyPath: "transform.scale")
        scale.fromValue = 1
        scale.toValue = 0.375
        scale.duration = 0.3
        scale.isRemovedOnCompletion = false
        scale.fillMode = .forwards

        let opacityFadeIn = CABasicAnimation(keyPath: "opacity")
        opacityFadeIn.fromValue = 0
        opacityFadeIn.toValue = 1
        opacityFadeIn.duration = 0.3
        opacityFadeIn.isRemovedOnCompletion = false
        opacityFadeIn.fillMode = .forwards

        let pulsing = CABasicAnimation(keyPath: "borderColor")
        pulsing.toValue = UIColor(white: 1, alpha: 0.5).cgColor
        pulsing.repeatCount = 2
        pulsing.duration = 0.2
        pulsing.beginTime = CACurrentMediaTime() + 0.3 // wait for the fade in to occur

        let opacityFadeOut = CABasicAnimation(keyPath: "opacity")
        opacityFadeOut.fromValue = 1
        opacityFadeOut.toValue = 0
        opacityFadeOut.duration = 0.5
        opacityFadeOut.beginTime = CACurrentMediaTime() + 2 // seconds
        opacityFadeOut.isRemovedOnCompletion = false
        opacityFadeOut.fillMode = .forwards

        focusBoxLayer.add(scale, forKey: scaleKey)
        focusBoxLayer.add(opacityFadeIn, forKey: fadeInKey)
        focusBoxLayer.add(pulsing, forKey: pulseKey)
        focusBoxLayer.add(opacityFadeOut, forKey: fadeOutKey)
    }

    // MARK: - Private Properties

    private lazy var focusBoxLayer: CALayer = {
        let box = CALayer()
        box.bounds = CGRect(x: 0, y: 0, width: 200, height: 200)
        box.borderWidth = 2
        box.borderColor = UIColor.white.cgColor
        box.opacity = 0
        return box
    }()

    // MARK: - Unsupported Initializers

    required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") }

}