线程1：致命错误：展开一个可选值（setupInputOutput）时意外发现nil

Question

我正在尝试向我的应用程序添加摄像头功能，但是这些消息一直显示在屏幕上，因此我无法为其找到解决方案。有什么可以代替的例子吗？

   func setupInputOutput(){
    do {
        let captureDeviceInput = try AVCaptureDeviceInput(device: currentCamera!);captureSession.addInput(captureDeviceInput)
        photoOutput?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format:[AVVideoCodecKey:  AVVideoCodecType.jpeg])], completionHandler: nil)

       } catch {print(error)

Answer 1

模拟器没有您需要在真实设备中运行的视频输入

func setupInputOutput() {  

   do { 
       guard let currentCamera = AVCaptureDevice.default(for: AVMediaType.video) else { return }
       let captureDeviceInput = try AVCaptureDeviceInput(device: currentCamera);captureSession.addInput(captureDeviceInput)
       photoOutput?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format:[AVVideoCodecKey:  AVVideoCodecType.jpeg])], completionHandler: nil)

   } catch {    
     print(error)

   } 

}