Swift error saying it cannot assign to property due to it being a 'let' constant

Here is the snippet of the code:

public var captureDevice: CaptureDevice?

...

guard let captureDeviceTest = AVCaptureDevice.DiscoverySession.init(
            deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera],
            mediaType: AVMediaType.video,
            position: cameraPosition).devices.first else {
                return
        }
        
self.captureDevice = captureDeviceTest
            
if let captureDevice = self.captureDevice {

   ...

   // This is where error occurs
   if captureDevice.isExposureModeSupported(.continuousAutoExposure) {
         captureDevice.exposureMode = .continuousAutoExposure
    }

The error I am getting is: Cannot assign to property: 'captureDevice' is a 'let' constant. I tried suggestion here to use inout but despite placing that in various places, it still didn’t work for me.

Any swift experts can help me out here?

>Solution :

You are accessing the local variable captureDevice, not the struct’s captureDevice variable.

Just replace the line causing the error to the following:

self?.captureDevice.exposureMode = .continuousAutoExposure

Note the self?. before captureDevice.