ios - 在 NSUserDefaults 中保存 Realm 对象子类？

Question

我正在将 Realm 引入到我的 swift 项目中。我有一个 User 类，我将其实例保存到 NSUserDefaults 中以跟踪第一个登录用户。

在使 User 成为 Object 的子类后，我在尝试取消存档时遇到以下错误(存档似乎工作正常):

Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: '*** -[NSKeyedUnarchiver decodeObjectForKey:]: cannot decode object of class (RLMStandalone_User) for key (root); the class may be defined in source code or a library that is not linked'

我将 Realm 安装为 Cocoapod，这是 User 类中的相关方法

static var currentUser: User? {
    get {
        if let data = NSUserDefaults.standardUserDefaults().objectForKey(UserDefaultKeys.kUserData) as? NSData,
            let user = NSKeyedUnarchiver.unarchiveObjectWithData(data) as? User {
            return user
        } else {
            return nil
        }
    }
    set {
        if let user = newValue {
            let data = NSKeyedArchiver.archivedDataWithRootObject(user)
            NSUserDefaults.standardUserDefaults().setObject(data, forKey: UserDefaultKeys.kUserData)
            NSUserDefaults.standardUserDefaults().synchronize()
        } else {
            NSUserDefaults.standardUserDefaults().removeObjectForKey(UserDefaultKeys.kUserData)
            NSUserDefaults.standardUserDefaults().synchronize()
        }
    }
}

// MARK: NSCoding

 convenience init?(coder decoder: NSCoder) {
    self.init()
    guard let firstName = decoder.decodeObjectForKey("firstName") as? String,
    let lastName = decoder.decodeObjectForKey("lastName") as? String,
    let email = decoder.decodeObjectForKey("email") as? String,
    let icloud = decoder.decodeObjectForKey("icloudUserID") as? String,
    let userType = decoder.decodeObjectForKey("userType") as? String
    else {
        return nil
    }

    self.firstName = firstName
    self.lastName = lastName
    self.email = email
    self.profilePic = decoder.decodeObjectForKey("profilePic") as? String
    self.icloudUserID = icloud
    self.userType = userType
    self.coverPhoto = decoder.decodeObjectForKey("coverPhoto") as? String
    self.facebookID = decoder.decodeObjectForKey("facebookID") as? String
    self.placeID = decoder.decodeObjectForKey("placeID") as? String
}

func encodeWithCoder(coder: NSCoder) {
    coder.encodeObject(self.firstName, forKey: "firstName")
    coder.encodeObject(self.lastName, forKey: "lastName")

    coder.encodeObject(self.icloudUserID, forKey: "icloudUserID")
    coder.encodeObject(self.userType, forKey: "userType")
    coder.encodeObject(email, forKey: "email")

    if let coverPhotoUrl = self.coverPhotoUrl {
        coder.encodeObject(coverPhotoUrl, forKey: "coverPhoto")
    }

    if let profilePicUrl = self.profilePicUrl {
        coder.encodeObject(profilePicUrl, forKey: "profilePic")
    }

    if let fbID = self.facebookID {
        coder.encodeObject(fbID, forKey: "facebookID")
    }

    if let placeID = self.placeID {
        coder.encodeObject(placeID, forKey: "placeID")
    }


}

Answer 1

不可能在 NSUserDefaults 中存储 Realm Object，因为(正如您在该错误消息中看到的那样)它们不能被 NSCoding< 序列化或反序列化 协议(protocol)。

相反，最好将主键属性添加到您的 User 对象(这样您就可以使用它从 Realm 中查询该对象)，并将主键本身存储在 NSUserDefaults 代替。

或者更好的是，与其依赖 NSUSerDefaults，不如简单地在您的模型中拥有一个 bool 属性 isCurrent，并使用它来计算出哪个更好用户是当前用户。