ios - NSGenericException，原因 : [AVCapturePhotoOutput capturePhotoWithSettings:delegate:] No active and enabled video connection

Question

我在尝试运行我的应用程序并拍摄照片时不断收到上述错误消息。

我是编程新手，所以如果有人能提供帮助那就太棒了。

这是我的代码

import UIKit
import AVFoundation
import Firebase


class CameraViewController: UIViewController, AVCapturePhotoCaptureDelegate, UITextViewDelegate, UITextFieldDelegate {

@IBOutlet weak var cameraView: UIView!
@IBOutlet weak var cancelButton: UIButton!
@IBOutlet weak var topButton: UIButton!
@IBOutlet weak var switchCamera: UIButton!
@IBOutlet weak var captionButton: UIButton!
@IBOutlet weak var takePhoto: UIButton!
@IBOutlet weak var postButton: UIButton!



var captureSession = AVCaptureSession()
var sessionOutput = AVCapturePhotoOutput()
var previewLayer = AVCaptureVideoPreviewLayer()
var settings = AVCapturePhotoSettings()


var ref = FIRDatabase.database().reference()
let storage = FIRStorage.storage()





override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    let deviceSession = AVCaptureDeviceDiscoverySession(deviceTypes: [.builtInDualCamera, .builtInTelephotoCamera, .builtInWideAngleCamera], mediaType: AVMediaTypeVideo, position: .unspecified)

    for device in (deviceSession?.devices)!{

        if device.position == AVCaptureDevicePosition.front {

            do{
                let input = try AVCaptureDeviceInput(device: device)
                if captureSession.canAddInput(input) {
                    captureSession.addInput(input)

                    if captureSession.canAddOutput(sessionOutput) {
                        captureSession.canAddOutput(sessionOutput)

                        previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                        previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
                        previewLayer.connection.videoOrientation = .portrait

                        cameraView.layer.addSublayer(previewLayer)


                        previewLayer.position = CGPoint (x: self.cameraView.frame.width / 2, y: self.cameraView.frame.height / 2)
                        previewLayer.bounds = cameraView.frame

                        captureSession.startRunning()
                    }
                }

            }catch let avError {
                print (avError)
            }
        }
    }
}



func capture(_ captureOutput: AVCapturePhotoOutput, didFinishProcessingPhotoSampleBuffer photoSampleBuffer: CMSampleBuffer?, previewPhotoSampleBuffer: CMSampleBuffer?, resolvedSettings: AVCaptureResolvedPhotoSettings, bracketSettings: AVCaptureBracketedStillImageSettings?, error: Error?) {

    if let error = error {
        print(error.localizedDescription)
        return
    }

    AppDelegate.instance().showActivityIndicator()

    let uid = FIRAuth.auth()!.currentUser!.uid
    let ref = FIRDatabase.database().reference()
    let storage = FIRStorage.storage().reference(forURL: "my url")

    if let sampleBuffer = photoSampleBuffer, let previewBuffer = photoSampleBuffer, let dataImage = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: sampleBuffer, previewPhotoSampleBuffer: previewBuffer) {

        let key = ref.child("posts").childByAutoId().key
        let imageRef = storage.child("posts").child(uid).child("\(key).jpg")

        let uploadTask = imageRef.put(dataImage, metadata: nil) {(metadata, error) in
            if error != nil {
                print(error!.localizedDescription)
                AppDelegate.instance().dismissActivityIndicator()
                return
            }
            imageRef.downloadURL(completion: {(url, error) in
                if let url = url {
                    let feed = ["userId" : uid,
                                "pathToImage" : url.absoluteString,
                                "likes" : 0,
                                "author" : FIRAuth.auth()?.currentUser!.displayName! as Any,
                                "postId" : key] as [String : Any]

                    let postFeed = ["\(key)" : feed]

                    ref.child("posts").updateChildValues(postFeed)
                    AppDelegate.instance().dismissActivityIndicator()

                    self.dismiss(animated: true, completion: nil)
                    self.postButton.isHidden = false
                }
            })


        }
        uploadTask.resume()
    }
    captureSession.stopRunning()
    previewLayer.removeFromSuperlayer()

}
@IBAction func takePhoto(_ sender: Any) {
    let previewPixelType = settings.availablePreviewPhotoPixelFormatTypes.first!
    let previewFormat = [kCVPixelBufferPixelFormatTypeKey as String : previewPixelType, kCVPixelBufferWidthKey as String : 160, kCVPixelBufferHeightKey as String : 160]

    settings.previewPhotoFormat = previewFormat
    self.sessionOutput.capturePhoto(with: settings, delegate: self)
    sessionOutput.isLivePhotoCaptureEnabled = true



}

@IBAction func cancelPressed(_ sender: Any) {

    dismiss(animated: true, completion: nil)

}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    self.view.endEditing(true)
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    textField.resignFirstResponder()
    return false

}


}

我想错误发生在这条线的某处 self.sessionOutput.capturePhoto(with: settings, delegate: self)

不过我不确定。我真的很感激一些帮助。谢谢!

Answer 1

您从未添加 sessionOutput，您调用了两次 canAddOutput 函数:

if captureSession.canAddOutput(sessionOutput) {
                    captureSession.canAddOutput(sessionOutput)

在检查是否可以添加之后，您应该在添加输入时添加输出

if captureSession.canAddOutput(sessionOutput) {
                    captureSession.addOutput(sessionOutput)

希望对你有帮助