ed5.swift

let panRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePan(_:)))
view.addGestureRecognizer(panRecognizer)
   
@objc func handlePan(_ gestureRecognize: UIPanGestureRecognizer) {
    let p = gestureRecognize.location(in: view)
    let hitResults = view.hitTest(p, options: [:])

    if hitResults.count > 0 {
        let result = hitResults[hitResults.count - 1].node as? NewNode
        let newPosition = p.scnVector3Value(view: view, depth: Float(result!.position.z))
        reassignNode(newNode: result!, newPosition: newPosition)
    }
}

func reassignNode(newNode: NewNode, newPosition:SCNVector3) {
    let indexOf = nodes.firstIndex { (node) -> Bool in
        node.uid == newNode.uid
    }
    if indexOf != nil {
        newNode.position = newPosition
        nodes[indexOf!] = newNode
    } else {
        assert(false,"NeverHappens")
    }
}