Взгляд камеры Swift 4, почему происходит сбой на iPad, а не на iPhone?

Question

Я создаю приложение для iPad, которое делает фотографии. Почему этот код вылетает на iPad, но отлично работает на iPhone? Я предполагаю, что это как-то связано с возможностями устройства? Я использую iPad Pro 12.9 под управлением iOS 12.1 и Swift 4.1 с Xcode 10. Я добавил необходимые строки в info.plist о конфиденциальности камеры и конфиденциальности фотографий. Спасибо за ваше руководство.

Вылетает в строке с оператором guard.

 private func configure() {
    // Preset the session for taking photo in full resolution
    captureSession.sessionPreset = AVCaptureSession.Preset.photo

    // Get the front and back-facing camera for taking photos
    let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera], mediaType: AVMediaType.video, position: .unspecified)

    for device in deviceDiscoverySession.devices {
        if device.position == .back {
            backFacingCamera = device
        } else if device.position == .front {
            frontFacingCamera = device
        }
    }

    currentDevice = backFacingCamera

    guard let captureDeviceInput = try? AVCaptureDeviceInput(device: currentDevice) else {
        return
    }

    // Configure the session with the output for capturing still images
    stillImageOutput = AVCapturePhotoOutput()

    // Configure the session with the input and the output devices
    captureSession.addInput(captureDeviceInput)
    captureSession.addOutput(stillImageOutput)

    // Provide a camera preview
    cameraPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    view.layer.addSublayer(cameraPreviewLayer!)
    cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
    cameraPreviewLayer?.frame = view.layer.frame

    // Bring the camera button to front
    view.bringSubviewToFront(cameraButton)
    captureSession.startRunning()

    // Toggle Camera recognizer
    toggleCameraGestureRecognizer.direction = .up
    toggleCameraGestureRecognizer.addTarget(self, action: #selector(toggleCamera))
    view.addGestureRecognizer(toggleCameraGestureRecognizer)

    // Zoom In recognizer
    zoomInGestureRecognizer.direction = .right
    zoomInGestureRecognizer.addTarget(self, action: #selector(zoomIn))
    view.addGestureRecognizer(zoomInGestureRecognizer)

    // Zoom Out recognizer
    zoomOutGestureRecognizer.direction = .left
    zoomOutGestureRecognizer.addTarget(self, action: #selector(zoomOut))
    view.addGestureRecognizer(zoomOutGestureRecognizer)
}

@objc func toggleCamera() {
    captureSession.beginConfiguration()

    // Change the device based on the current camera
    guard let newDevice = (currentDevice?.position == AVCaptureDevice.Position.back) ? frontFacingCamera : backFacingCamera else {
        return
    }

    // Remove all inputs from the session
    for input in captureSession.inputs {
        captureSession.removeInput(input as! AVCaptureDeviceInput)
    }

    // Change to the new input
    let cameraInput:AVCaptureDeviceInput
    do {
        cameraInput = try AVCaptureDeviceInput(device: newDevice)
    } catch {
        print(error)
        return
    }

    if captureSession.canAddInput(cameraInput) {
        captureSession.addInput(cameraInput)
    }

    currentDevice = newDevice
    captureSession.commitConfiguration()
}

Answer 1

Это возможности устройства.У iPad есть широкоугольная камера.

 let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .unspecified)