swift - AVFoundation Camera in view

Question

I'm having a lot of problems trying to get a view to show my back Camera feed. I looked throughout apples docs and came up with this, but all it seems to do is make a black screen. I also added the perms in my plist and am running on a real device. I don't need it to take a photo or save anything. Just simply show the camera live in a view.

import UIKit
import AVFoundation

class ViewController: UIViewController {

    
    @IBOutlet weak var cameraView: UIView!
    
    
    var captureSession = AVCaptureSession()
    var previewLayer = AVCaptureVideoPreviewLayer()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        loadCamera()
    }

    func loadCamera() {
        
        let device = AVCaptureDevice.default(.builtInWideAngleCamera, for: AVMediaType.video, position: .back)
        
        do {
            let input = try AVCaptureDeviceInput(device: device!)
            
            if captureSession.canAddInput(input) {
                captureSession.addInput(input)
                
                previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
                previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
                previewLayer.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
                cameraView.layer.addSublayer(previewLayer)
                
            }
            
        } catch {
            print(error)
        }
    }  
}

question from:https://stackoverflow.com/questions/66057622/avfoundation-camera-in-view

Answer 1

Welcome!

The problem is that there is actually no data flow (of video frames) happening with your current setup. You need to at least attach one input and one output to your capture session. The preview layer doesn't count as an output itself since it will only attach to an existing connection between input and output.

So to fix it, you can just add an AVCapturePhotoOutput to the session (probably before you add the layer) but never use it. The preview layer should start displaying the frames then.

You probably also want to set the session's sessionPreset to .photo before you add the inputs and outputs. This will cause the session to produce video frames that have an ideal size for displaying on your device's screen.