Grab frames in Vision Pro using ARFrame

I'd like to grab the current camera frame in visionOS. I have a Swift file (am new to Swift) that looks like this:

import ARKit
import SwiftUI

class ARSessionManager: NSObject, ObservableObject, ARSessionDelegate {
    var arSession: ARSession
    
    override init() {
        arSession = ARSession()
        super.init()
        arSession.delegate = self
    }
    
    func startSession() {
        let configuration = ARWorldTrackingConfiguration()
        configuration.planeDetection = .horizontal
        arSession.run(configuration)
    }
    
    // ARSessionDelegate method to capture frames
    func session(_ session: ARSession, didUpdate frame: ARFrame) {
        // Process the frame, e.g., capture image data
    }
}

and I get errors including "Cannot find type 'ARSessionDelegate' in scope". Help? Is ARFrame called something different for Vision Pro?