This sample code is not correct.

[jaws241]

@IBAction func changeCameraQuality() {
    switch cameraManager.cameraOutputQuality {
        case .high:
            qualityLabel.text = "Medium"
            cameraManager.cameraOutputQuality = .medium
        case .medium:
            qualityLabel.text = "Low"
            cameraManager.cameraOutputQuality = .low
        case .low:
            qualityLabel.text = "High"
            cameraManager.cameraOutputQuality = .high
        default:
            qualityLabel.text = "High"
            cameraManager.cameraOutputQuality = .high
    }
}

Should it be:
@IBAction func changeCameraQuality() {
switch cameraManager.cameraOutputQuality {
case .medium:
qualityLabel.text = "Medium"
cameraManager.cameraOutputQuality = .medium
case .low:
qualityLabel.text = "Low"
cameraManager.cameraOutputQuality = .low
case .high:
qualityLabel.text = "High"
cameraManager.cameraOutputQuality = .high
default:
qualityLabel.text = "High"
cameraManager.cameraOutputQuality = .high
}
}