Ios 如何更改前置摄像头的曝光？

经过反复试验，我发现iPhone 6及以下版本的前置摄像头不支持点击对焦。然而，有没有办法改变曝光？我尝试了下面的代码，但什么也没发生。使用这种方法后摄像头的焦距很好，但当我切换到前摄像头时，什么也没有发生。（我使用的是定制相机）

任何帮助都将不胜感激

- (void) focusAtPoint:(CGPoint)point

{
AVCaptureDevice *device = [deviceInput device];

NSArray * inputs = session.inputs;
for (AVCaptureDeviceInput * INPUT in inputs) {
    AVCaptureDevice * Device = INPUT.device ;
    if ([ Device hasMediaType:AVMediaTypeVideo ]) {
        AVCaptureDevicePosition position = Device.position;


        if (position == AVCaptureDevicePositionFront)
        {
            //code for setting exposure
            if ([device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
                NSError *error;

                [device lockForConfiguration:&error];

                CGPoint exposurePoint = point;
                [device setExposurePointOfInterest:exposurePoint];
                [device setExposureMode:AVCaptureExposureModeContinuousAutoExposure];
                [device unlockForConfiguration];
            }

        }
        else if(position == AVCaptureDevicePositionBack)
        {
           //code for focusing 
        }

    }
} 
}

它可以帮助你

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.y / frameSize.height
                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.devices().first as? AVCaptureDevice

                let captureDevice = (AVCaptureDevice.devicesWithMediaType(AVMediaTypeVideo) as! [AVCaptureDevice]).filter{$0.position == .Front}.first

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

                        let focusSupport:Bool = device.focusPointOfInterestSupported
                        let exposureSupport:Bool = device.exposurePointOfInterestSupported

                        print(" AVCaptureFocusMode.AutoFocus:  \(device.isFocusModeSupported(AVCaptureFocusMode.AutoFocus))")
                        print(" AVCaptureFocusMode.ContinuousAutoFocus:  \(device.isFocusModeSupported(AVCaptureFocusMode.ContinuousAutoFocus))")
                        print(" AVCaptureFocusMode.Locked:  \(device.isFocusModeSupported(AVCaptureFocusMode.Locked))")

                        print(" AVCaptureExposureMode.AutoExpose:  \(device.isExposureModeSupported(AVCaptureExposureMode.AutoExpose))")
                        print(" AVCaptureExposureMode.ContinuousAutoExposure:  \(device.isExposureModeSupported(AVCaptureExposureMode.ContinuousAutoExposure))")
                        print(" AVCaptureExposureMode.Locked:  \(device.isExposureModeSupported(AVCaptureExposureMode.Locked))")


                        if focusSupport  {

                            print("focusPointOfInterestSupported: \(focusSupport)")

                            device.focusPointOfInterest = focusPoint

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


                            print("Focus point was set successfully")
                        }
                        else{
                            print("focusPointOfInterestSupported is not supported: \(focusSupport)")
                        }


                        if exposureSupport {

                            print("exposurePointOfInterestSupported: \(exposureSupport)")

                            device.exposurePointOfInterest = focusPoint

                            device.exposureMode = AVCaptureExposureMode.ContinuousAutoExposure

                            print("Exposure point was set successfully")
                        }
                        else{
                            print("exposurePointOfInterestSupported is not supported: \(exposureSupport)")
                        }

                        device.unlockForConfiguration()

                    }
                    catch {
                        // just ignore
                        print("Focus point error")
                    }
                }

覆盖函数触摸开始（触摸：设置，withEvent事件：UIEvent？）{
让screenSize=cameraView.bounds.size
let frameSize:CGSize=view.frame.size
如果让touchPoint=touchs.first{
变量位置：CGPoint=touchPoint.locationInView（cameraView）
打印（“点击位置：X:\（Location.X），Y:\（Location.Y）”）
如果cameraManager.cameraDevice==.Front{
打印（“使用前摄像头”）
location.x=frameSize.width-location.x；
}
否则{
打印（“使用后摄像头”）
}
//设x=位置.y/框架尺寸.height
设x=location.x/frameSize.width
设y=1.0-（location.x/frameSize.width）
设focusPoint=CGPoint（x:x，y:y）
打印（“点：X:\（X），Y:\（Y）”）
//设captureDevice=AVCaptureDevice.devices（）。首先为？AVCaptureDevice
让captureDevice=（AVCaptureDevice.devicesWithMediaType（AVMediaTypeVideo）作为！[AVCaptureDevice]）。筛选器{$0.position=.Front}。首先
如果let device=captureDevice{
做{
请尝试device.lockForConfiguration（）
let focusSupport:Bool=device.focusPointOfInterestSupported
让exposureSupport:Bool=device.exposurePointOfInterestSupported
打印（“AVCaptureFocusMode.AutoFocus:\（device.isFocusModeSupported（AVCaptureFocusMode.AutoFocus））”）
打印（“AVCaptureFocusMode.ContinuousAutoFocus:\（设备.isFocusModeSupported（AVCaptureFocusMode.ContinuousAutoFocus）））
打印（“AVCaptureFocusMode.Locked:\（device.isFocusModeSupported（AVCaptureFocusMode.Locked）））
打印（“AVCaptureExposureMode.AutoExposure:\（设备.IsExposureMode支持（AVCaptureExposureMode.AutoExpose）））
打印（“AVCaptureExposureMode.ContinuousAutoExposure:\（设备.IsExposureMode支持（AVCaptureExposureMode.ContinuousAutoExposure）））
打印（“AVCaptureExposureMode.Locked:\（device.isExposureModeSupported（AVCaptureExposureMode.Locked）））
如果聚焦支持{
打印（“focusPointOfInterestSupported:\（focusSupport）”）
device.focusPointOfInterest=焦点点
//device.focusMode=.ContinuousAutoFocus
device.focusMode=.AutoFocus
//device.focusMode=.Locked
打印（“焦点设置成功”）
}
否则{
打印（“不支持focusPointOfInterestSupported:\（focusSupport）”）
}
如果公开支持{
打印（“exposurePointOfInterestSupported:\（exposureSupport）”）
device.exposurePointOfInterest=焦点点
device.exposureMode=AVCaptureExposureMode.ContinuousAutoExposure
打印（“曝光点设置成功”）
}
否则{
打印（“不支持exposurePointOfInterestSupported:\（exposureSupport）”）
}
device.unlockForConfiguration（）
}
抓住{
//不管
打印（“焦点错误”）
}
}

您找到了解决方案吗？您也能用前置摄像头对焦吗？