Preview layer not being constrained to uiview

My Swift code below is trying to constrain the previewLayer to the bounds of the UIView which is named camera view. However that is not happening. The previewLayer is much bigger than the constraint cameraView UIView. The cameraView is constrained via storyboard constraints. I just want the 2 objects to be the same position and size.

             import AVFoundation
    import UIKit

     class ViewController: UIViewController, AVCaptureFileOutputRecordingDelegate {

      func fileOutput(_ output: AVCaptureFileOutput, didFinishRecordingTo outputFileURL: URL, from connections: [AVCaptureConnection], error: Error?) {


    var captureSession = AVCaptureSession()
   var sessionOutput = AVCaptureStillImageOutput()
    var movieOutput = AVCaptureMovieFileOutput()
    var previewLayer = AVCaptureVideoPreviewLayer()

     @IBOutlet var cameraView: UIView!

  override func viewWillAppear(_ animated: Bool) {
   self.cameraView = self.view

   let devices = AVCaptureDevice.devices(for:
   for device in devices {
       if device.position == AVCaptureDevice.Position.front {
           do {
               let input = try AVCaptureDeviceInput(device: device)
               if captureSession.canAddInput(input){
                   sessionOutput.outputSettings = [AVVideoCodecKey : AVVideoCodecType.jpeg]
                   if captureSession.canAddOutput(sessionOutput) {

                       previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                       previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
                       previewLayer.connection!.videoOrientation = AVCaptureVideoOrientation.portrait

                       previewLayer.bounds = cameraView.frame



                   let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
                   let documentURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
                   let fileURL = documentURL.appendingPathComponent("tempImage.jpg")
                   try? FileManager.default.removeItem(at: fileURL)
                   movieOutput.startRecording(to: fileURL, recordingDelegate: self)

                   let deadlineTime = + .seconds(1)
                   DispatchQueue.main.asyncAfter(deadline: deadlineTime) {
           catch {

   func captureOutput(captureOutput: AVCaptureFileOutput!, didFinishRecordingToOutputFileAtURL outputFileURL: NSURL!, fromConnections connections: [AnyObject]!, error: NSError!) {
   print("FINISHED \(error)")
   // save video to camera roll
   if error == nil {
       UISaveVideoAtPathToSavedPhotosAlbum(outputFileURL.path!, nil, nil, nil)

Hey, you may have already figured this out. But the trick is to start the session and then fit the preview layer to the UIView frame bounds. Saw it here:

Good luck!

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