IOS13中的ARBodyTracking :如何获得身体关节的真实世界坐标？

import ARKit

class ViewController: UIViewController, ARSessionDelegate {
    var arSession: ARSession!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        arSession = ARSession()
        arSession.delegate = self
        
        let configuration = ARBodyTrackingConfiguration()
        arSession.run(configuration)
    }
    
    func session(_ session: ARSession, didUpdate frame: ARFrame) {
        guard let bodyAnchor = frame.capturedBody else { return }
        
        for jointName in ARSkeletonDefinition.defaultBody3D.jointNames {
            guard let jointIndex = bodyAnchor.skeleton.index(for: jointName) else { continue }
            let jointTransform = bodyAnchor.skeleton.jointModelTransforms[jointIndex]
            
            let jointPosition = jointTransform.columns.3
            let jointWorldPosition = simd_make_float4(jointPosition.x, jointPosition.y, jointPosition.z, 1)
            let jointWorldCoordinates = simd_mul(bodyAnchor.transform, jointWorldPosition)
            
            // 使用jointWorldCoordinates获取关节的真实世界坐标
        }
    }
}