swift - PFUser 到自定义模型

Question

我有一个从 Parse 为我的 PFUser 构建的模型:

import Foundation
import Parse

class TradeUser : PFUser {

override class func initialize() {
    self.registerSubclass()
}

var userID : String {
    get {return objectForKey("objectId") as! String}
    set { setObject(newValue, forKey: "objectId") }
}

var emailAddress : String {
    get {return objectForKey("email") as! String}
    set { setObject(newValue, forKey: "email") }
}

var firstName : String {
    get {return objectForKey("firstName") as! String}
    set {setObject(newValue, forKey: "firstName")}
}

var lastName : String {
    get {return objectForKey("lastName") as! String}
    set {setObject(newValue, forKey: "lastName")}
}

var primaryQueue : String {
    get {return objectForKey("primaryQueue") as! String}
    set {setObject(newValue, forKey: "primaryQueue")}
}

var image : PFFile {
    get { return self["profileImage"] as! PFFile }
    set { self["profileImage"] = newValue }
}
}

但是，当我查询获取用户并尝试将其转换为该用户时，我收到“无法将类型‘PFUser’(0x107555928)的值转换为‘ShiftSwap.TradeUser’(0x10754e910)。”

我认为 TradeUser 与 PFUser 具有相同的值类型，因为它是 PFUser 转换？我有点困惑，任何澄清将不胜感激!

编辑:

@IBAction func chatBarButton(sender: AnyObject) {

    let postingUser = self.object?.objectForKey("userID") as! String

    let tradeUserQuery = PFUser.query()
    tradeUserQuery?.whereKey("objectId", equalTo: postingUser)
    let trader = tradeUserQuery?.getFirstObject() as! TradeUser

    var chatVC = MessagesViewController()

    chatVC.currentUser = TradeUser.currentUser()
    print(TradeUser.currentUser())
    chatVC.otherUser = trader

    self.navigationController?.pushViewController(chatVC, animated: true)

}

Answer 1

你正在强制自己沮丧，这是不可能的。您不能将基类 PFUser 的实例向下转换为派生的 TradeUser。