如何使用Parse邀请用户加入多人游戏会话(swift)

let gameSession = PFObject(className: "GameSession")
gameSession["name"] = "多人游戏会话"
gameSession.saveInBackground { (success, error) in
    if success {
        // 会话对象保存成功
    } else {
        // 会话对象保存失败，处理错误
    }
}

let invitation = PFObject(className: "Invitation")
invitation["gameSession"] = gameSession
invitation["inviter"] = PFUser.current()
invitation["invitee"] = inviteeUser // inviteeUser为被邀请的用户对象
invitation.saveInBackground { (success, error) in
    if success {
        // 邀请对象保存成功
    } else {
        // 邀请对象保存失败，处理错误
    }
}

let query = PFQuery(className: "Invitation")
query.whereKey("invitee", equalTo: PFUser.current())
query.findObjectsInBackground { (invitations, error) in
    if let invitations = invitations {
        // 处理查询到的邀请对象
    } else {
        // 查询邀请对象失败，处理错误
    }
}