ios 9 AVCaptureDevice设置焦点

Question

我正在尝试使用前置摄像头设置焦点。

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {

    let screenSize = cameraView.bounds.size

    let frameSize:CGSize = view.frame.size

    if let touchPoint = touches.first {

        var location:CGPoint = touchPoint.locationInView(cameraView)

        print("Tap Location : X: \(location.x), Y: \(location.y)")

        if cameraManager.cameraDevice == .Front {
            print("Front camera is used")

            location.x = frameSize.width - location.x;
        }
        else {
            print("Back camera is used")
        }

        let x = location.x / frameSize.width
        let y = 1.0 - (location.x / frameSize.width)

        let focusPoint = CGPoint(x: x, y: y)

        print("POINT : X: \(x), Y: \(y)")


        let captureDevice = (AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo) as! [AVCaptureDevice]).filter{[=11=].position == .Front}.first

        if let device = captureDevice {
            do {
                try device.lockForConfiguration()

                let support:Bool = device.focusPointOfInterestSupported

                if support  {

                    print("focusPointOfInterestSupported: \(support)")

                    device.focusPointOfInterest = focusPoint

                    // device.focusMode = .ContinuousAutoFocus
                    device.focusMode = .AutoFocus
                    // device.focusMode = .Locked

                    device.unlockForConfiguration()

                    print("Focus point was set successfully")
                }
                else{
                    print("focusPointOfInterestSupported is not supported: \(support)")
                }
            }
            catch {
                // just ignore
                print("Focus point error")
            }
        }
    }
}

它适用于 iphone6 的后置摄像头。但是，当我启动前置摄像头时，它出现了抖动。 focusPointOfInterestSupported 总是 returns false。

我该如何解决这个问题。我可以通过编程方式设置焦点吗？

谢谢！

Answer 1

focusPointOfInterestSupported 布尔值表示此设备的前置摄像头不支持以这种方式设置焦点。事实上，iPhone 6 的 "FaceTime" 相机似乎具有固定焦距。 iPhone 6 "FaceTime" 摄像头的技术规格部分没有提及 "focus"，但在后置 "iSight" 摄像头部分有提及。此外，尝试将前置摄像头重新聚焦在靠近镜头的模糊物体上（通过在“相机”应用中点击）似乎只能调整曝光，而不能调整焦点。

来源：https://developer.apple.com/library/ios/documentation/AVFoundation/Reference/AVCaptureDevice_Class/index.html#//apple_ref/occ/instp/AVCaptureDevice/focusPointOfInterestSupported

来源：http://www.apple.com/iphone-6/specs/

ios 9 AVCaptureDevice设置焦点

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