在NSUserDefaults中存儲自定義對象時應用程序崩潰

Question

我有自定義類名爲User的女巫符合NSCoding協議。但是，當我試圖存儲它NSUserDefaults的中我得到這個錯誤：

Property list invalid for format: 200 
(property lists cannot contain objects of type 'CFType') 

而且這樣的警告：

NSForwarding: warning: object 0x7f816a681110 of class 'Shikimori.User' 
does not implement methodSignatureForSelector: -- trouble ahead 
Unrecognized selector -[Shikimori.User _copyDescription] 

User類：

class User: NSCoding { 

private enum CoderKeys: String { 
    case ID = "user.id" 
    case Username = "user.username" 
    case Email = "user.email" 
    case Avatar = "user.avatar" 
} 

let id: Int 
let username: String 
let email: String 
let avatar: String 

init(id: Int, username: String, email: String, avatar: String) { 
    self.id = id 
    self.username = username 
    self.email = email 
    self.avatar = avatar 
} 

required init(coder aDecoder: NSCoder) { 
    id = aDecoder.decodeIntegerForKey(CoderKeys.ID.rawValue) 
    username = aDecoder.decodeObjectForKey(CoderKeys.Username.rawValue) as String 
    email = aDecoder.decodeObjectForKey(CoderKeys.Email.rawValue) as String 
    avatar = aDecoder.decodeObjectForKey(CoderKeys.Avatar.rawValue) as String 
} 

func encodeWithCoder(aCoder: NSCoder) { 
    aCoder.encodeInteger(id, forKey: CoderKeys.ID.rawValue) 
    aCoder.encodeObject(username as NSString, forKey: CoderKeys.Username.rawValue) 
    aCoder.encodeObject(email as NSString, forKey: CoderKeys.Email.rawValue) 
    aCoder.encodeObject(avatar as NSString, forKey: CoderKeys.Avatar.rawValue) 
} 
} 

更新 保存代碼：

let userKeyForDefaults = "apimanager.user" 


let defaults = NSUserDefaults.standardUserDefaults() 
defaults.setObject(user, forKey: self.userKeyForDefaults) 

Answer 1

NSUserDefaults不支持所有對象，只是像NSString,NSDictionary，最重要的是NSData。這是NSCoding協議派上用場的地方。它允許我們將自定義對象轉換爲大塊NSData。要做到這一點，使用NSKeyedArchiver類把符合自定義對象NSCoding等效NSData

let obj = User() 
let data = NSKeyedArchiver. archivedDataWithRootObject(obj) 
/// Now you can store data 

的文檔可以發現here和你正在尋找的方法是

class func archivedDataWithRootObject(_ rootObject: AnyObject) -> NSData 

要拿東西出的NSUserDefaults，用「反」類，NSKeyedUnarchiver。其適當的方法如下

class func unarchiveObjectWithData(_ data: NSData) -> AnyObject? 

下面是一個示例。

let data = NSUserDefaults.standardUserDefaults().objectForKey("somekey") 
let obj = NSKeyedUnarchiver. unarchiveObjectWithData(data) as User? 

注：我可能混雜了一些optionals，但你得到了jist。 NSKeyedUnarchiver的文檔可以找到here。

編輯：解決OP的問題就像正確使用NSKeyedArchiver和子類NSObject一樣簡單。