Swift 3-AVCapture自定义摄像头视图

我一直在看这段视频，制作一个定制的摄像头视图。

然而，由于iOS 10和swift 3的变化，许多事情不再相关了

下面是我在将不推荐的函数更改为新函数后得到的代码。但是没有错误，但是在UIView上也没有看到预览

import UIKit
import AVFoundation

class ViewController: UIViewController, AVCapturePhotoCaptureDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    @IBOutlet weak var cameraView: UIView!
    var captureSession = AVCaptureSession();
    var sessionOutput = AVCapturePhotoOutput();
    var sessionOutputSetting = AVCapturePhotoSettings(format: [AVVideoCodecKey:AVVideoCodecJPEG]);
    var previewLayer = AVCaptureVideoPreviewLayer();

    override func viewWillAppear(_ animated: Bool) {
        let deviceDiscoverySession = AVCaptureDeviceDiscoverySession(deviceTypes: [AVCaptureDeviceType.builtInDuoCamera, AVCaptureDeviceType.builtInTelephotoCamera,AVCaptureDeviceType.builtInWideAngleCamera], mediaType: AVMediaTypeVideo, position: AVCaptureDevicePosition.unspecified)
        for device in (deviceDiscoverySession?.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.addOutput(sessionOutput);
                            previewLayer = AVCaptureVideoPreviewLayer(session: captureSession);
                            previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
                            previewLayer.connection.videoOrientation = AVCaptureVideoOrientation.portrait;
                            cameraView.layer.addSublayer(previewLayer);
                        }
                    }
                }
                catch{
                    print("exception!");
                }
            }
        }
    }

---

您忘记启动会话：

captureSession.startRunning()

并为您的

预览层设置帧

：

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    previewLayer.frame = cameraView.bounds
}

---

p、 一旦你添加了会话输入和输出，你就应该打破这个循环。

不管怎样，它应该只运行一次？可能吧，但这让我感到紧张。例如，iPhone 7+上不是有两个背向摄像头吗？这不太可能，但你可能会在未来的硬件上得到一个令人讨厌的惊喜…是的，肯定会打破循环。如果可能，请始终避免将来出现问题。@hyrthmicfistman在

previewLayer.frame=cameraView.bounds

行上崩溃。

sessionOutputSetting

未使用…为什么？