Swift 4 相机视图，为啥这会在 iPad 而不是 iPhone 上崩溃？

Posted 2023-03-12

【中文标题】Swift 4 相机视图，为啥这会在 iPad 而不是 iPhone 上崩溃？

【英文标题】：Swift 4 camera view, why does this crash on iPad and not on iPhone?Swift 4 相机视图，为什么这会在 iPad 而不是 iPhone 上崩溃？

【发布时间】：2018-11-19 21:01:16

【问题描述】：

我正在为 iPad 构建一个可以拍照的应用程序。为什么这段代码在 iPad 上会崩溃，但在 iPhone 上却能正常运行？我假设它与设备功能有关？我正在使用运行 ios 12.1 和 Swift 4.1 的 iPad Pro 12.9 和 Xcode 10。我在 info.plist 中添加了有关相机隐私和照片隐私的必要行。感谢您的指导。

它在guard 语句的行处崩溃。

 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()

【问题讨论】：

嘿，面临同样的问题，但在 Iphone 设备上，让我知道您的解决方案是什么

【参考方案1】：

这是设备功能。 iPad 有广角摄像头。

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