仅在 iPhone 7 之前的设备上使用前置摄像头时发生崩溃

我最近开始在基于相机的应用程序上运行测试版。除 iPhone 6 设备外，一切都按预期运行。

会话从后置摄像头开始，每次 iPhone 6 用户切换到前置摄像头时，应用程序都会崩溃。 （需要明确的是：任何其他 iPhone 型号上都没有人遇到此问题。）我已经拿到了 6 进行测试，并且可以一致地重现该错误，从而导致libc++abi.dylib: terminating with uncaught exception of type NSException.

我尝试在前置摄像头上启动会话，但它立即崩溃。

func initializeCamera() {
    self.captureSession.sessionPreset = .hd1920x1080

    let discovery = AVCaptureDevice.DiscoverySession.init(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera],
                                                          mediaType: .video,
                                                          position: .unspecified) as AVCaptureDevice.DiscoverySession

    for device in discovery.devices as [AVCaptureDevice] {
        if device.hasMediaType(.video) {
            if device.position == AVCaptureDevice.Position.front {
                videoCaptureDevice = device
                do {
                    try currentDeviceInput = AVCaptureDeviceInput(device: device)
                } catch {
                    print("error: \(error.localizedDescription)")
                }
            }
        }
    }

    if videoCaptureDevice != nil {
        do {
            let videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice!)
            captureSession.addInput(videoInput)

            if let audioInput = AVCaptureDevice.default(for: .audio) {
                try captureSession.addInput(AVCaptureDeviceInput(device: audioInput))
            }

            previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)

            guard let previewLayer = previewLayer else { return }

            cameraPreviewView.frame = cameraContainer.frame

            cameraPreviewView.layer.addSublayer(previewLayer)
            previewLayer.frame = cameraPreviewView.frame

            previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill

            setVideoOrientation()

            captureSession.addOutput(movieFileOutput)

            if let movieFileOutputConnection = movieFileOutput.connection(with: .video) {
                if movieFileOutputConnection.isVideoStabilizationSupported {
                    movieFileOutputConnection.preferredVideoStabilizationMode = .cinematic
                }
            }

            captureSession.startRunning()

            sessionIsReady(true)

        } catch {
            print("error: \(error.localizedDescription)")
        }
    }

}
func setVideoOrientation() {
    if let connection = self.previewLayer?.connection {
        if connection.isVideoOrientationSupported {
            connection.videoOrientation = .portrait
            previewLayer?.frame = cameraContainer.bounds
        }
    }
}

崩溃触发于captureSession.addInput(videoInput). videoInput is not nil。相机方向锁定为纵向。

任何人都可以提供任何见解吗？如果任何其他代码有帮助，请告诉我。提前致谢。

captureSession.addInput(videoInput)导致了崩溃。

所以你应该使用canAddInput(_:)之前避免崩溃。

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

就你而言，captureSession.canAddInput(videoInput)== iPhone 6 为 false。

现在，你也在做self.captureSession.sessionPreset = .hd1920x1080

But 根据维基百科，iPhone 6前置摄像头硬件支持摄像头 1.2 MP（最大 1280×960 像素），720p 视频录制（30 fps）。似乎不适合 1920*1080（“全高清”）。

你可以这样做检查“最大”AVCaptureSession.Preset您可以使用。

func setSessionPreset(forDevice device: AVCaptureDevice) {
    let videoPresets: [AVCaptureSession.Preset] = [.hd4K3840x2160, .hd1920x1080, .hd1280x720] //etc. Put them in order to "preferred" to "last preferred"
    let preset = videoPresets.first(where: { device.supportsSessionPreset($0) }) ?? .hd1280x720
    captureSession.sessionPreset = preset
}