AVCapturePhotoOutput - 设置不可重复使用

Question

我正在运行 ios 12 swift 4.2。

我已经实现了一个基本的相机捕获会话，并且正在点击其中的图像。一切都很好，直到我在自动/开/关模式之间切换闪光灯。单击第一张照片然后更改闪光模式后，应用程序崩溃并显示错误：

[AVCapturePhotoOutput capturePhotoWithSettings:delegate:] Settings may not be re-used'

以下是相机实现：

var captureSession: AVCaptureSession!
var videoPreviewLayer: AVCaptureVideoPreviewLayer!
var capturePhotoOutput: AVCapturePhotoOutput!
let capturePhotoSettings = AVCapturePhotoSettings()


var previewView: UIView!


override func viewDidLoad() {
    startCameraSession()
    setupCaptureOutput()
}

@objc // Tap on a button to capture
func takePhotoOnTap() {
    guard let capturePhotoOutput = self.capturePhotoOutput else { return }

    capturePhotoSettings.isAutoStillImageStabilizationEnabled = true
    capturePhotoSettings.isHighResolutionPhotoEnabled = true
    capturePhotoSettings.flashMode = .auto
    let _ = getSettings(camera: captureDevice!, flashMode: spotmiCameraOptions.flashMode)
    capturePhotoOutput.capturePhoto(with: capturePhotoSettings, delegate: self)
}


    //This is a delegate method from the button
func toggleFlash(mode: FlashMode) {

    switch mode {
    case .auto:
        capturePhotoSettings.flashMode = .auto
    case .enabled:
        capturePhotoSettings.flashMode = .on
    case .disabled:
        capturePhotoSettings.flashMode = .off
    }

}


func setupCaptureOutput() {
    capturePhotoOutput = AVCapturePhotoOutput()
    capturePhotoOutput.isHighResolutionCaptureEnabled = true
    captureSession.addOutput(capturePhotoOutput)
}

func startCameraSession() {

    let captureDevice = AVCaptureDevice.default(.builtInDualCamera, for: AVMediaType.video, position: .back)

    do {
        let input = try AVCaptureDeviceInput(device: captureDevice!)
        captureSession = AVCaptureSession()
        captureSession.addInput(input)
        videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        videoPreviewLayer.videoGravity = .resizeAspectFill
        videoPreviewLayer.frame = self.view.layer.bounds
        camcontainer.layer.addSublayer(videoPreviewLayer)
        captureSession.startRunning()
    } catch {
        print(error.localizedDescription)
    }


}

func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photoSampleBuffer: CMSampleBuffer?, previewPhoto previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {
    guard error == nil, let sampleBuffer = photoSampleBuffer else {
        print("error capturing photo due to \(String(describing: error?.localizedDescription))")
        return
    }
    guard let imageData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: sampleBuffer, previewPhotoSampleBuffer: previewPhotoSampleBuffer) else  { return }

    let capturedImage = UIImage(data: imageData, scale: 1.0)
    if let image = capturedImage {
        UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)
    }
}

    func getSettings(camera: AVCaptureDevice, flashMode: FlashMode) -> AVCapturePhotoSettings {
    let settings = capturePhotoSettings

    if camera.hasFlash {
        switch flashMode {
//            case .auto: settings.flashMode = .auto
        case .enabled: settings.flashMode = .on
        case .disabled: settings.flashMode = .off
        default: settings.flashMode = .auto
        }
    }
    return settings
}

我真的不明白如何准确地重用captureSettings并每次使用不同的闪光模式更改它。我遇到了几个问题，但它们主要是关于手电筒的。我正在寻找闪光灯。

很感谢任何形式的帮助。

Answer 1

AVCapturePhotoSettings 对象是唯一的，不能重复使用，因此每次使用此方法时都需要获取新设置：

func getSettings(camera: AVCaptureDevice, flashMode: CurrentFlashMode) -> AVCapturePhotoSettings {
    let settings = AVCapturePhotoSettings()

    if camera.hasFlash {
        switch flashMode {
           case .auto: settings.flashMode = .auto
           case .on: settings.flashMode = .on
           default: settings.flashMode = .off
        }
    }
    return settings
}

如您所见，lockConfiguration不需要。

CurrentFlashModeis enum，它的创建是为了让事情变得清晰：

enum CurrentFlashMode { case off case on case auto }

然后只需在拍摄照片时使用它：

 @IBAction func captureButtonPressed(_ sender: UIButton) {
        let currentSettings = getSettings(camera: currentCamera, flashMode: currentFlashMode)
        photoOutput.capturePhoto(with: currentSettings, delegate: self)
    }