无法分配给'localVc'的属性，哪个是仅获取对象？

Question

就像下面的代码一样，为什么swift不允许为只读对象赋值属性?只读对象localVc具有设置写入属性"refreshGesture"

public protocol HVSHomeVideoChildProtocol {
var refreshGesture: UIPanGestureRecognizer! {get set}
}
class HVSHomeLocalVideoController: HVSHomeVideoChildProtocol {
public var refreshGesture: UIPanGestureRecognizer!
}

typealias HVSHomeVideoController = (UIViewController & HVSHomeVideoChildProtocol)
@objc(HSAVideoHomeViewController)
class HSAVideoHomeViewController: UIViewController {

var refreshGesture: UIPanGestureRecognizer!
let singleLocalVc = HVSHomeLocalVideoController.init()  
var localVc: HVSHomeVideoController {
return singleLocalVc
}

public override func viewDidLoad() {
super.viewDidLoad()
refreshGesture = UIPanGestureRecognizer.init(target: self, action: #selector(refreshGestureAction(sender:)))
localVc.refreshGesture = refreshGesture
}
}

Answer 1

变化

public protocol HVSHomeVideoChildProtocol {
var refreshGesture: UIPanGestureRecognizer! {get set}
}

public protocol HVSHomeVideoChildProtocol : AnyObject {
var refreshGesture: UIPanGestureRecognizer! {get set}
}