尝试在 Swift 3 中保存自定义对象时尝试插入非属性列表对象

Question

我有一个符合NSCoding 协议的简单对象。

import Foundation

class JobCategory: NSObject, NSCoding {
    var id: Int
    var name: String
    var URLString: String

    init(id: Int, name: String, URLString: String) {
        self.id = id
        self.name = name
        self.URLString = URLString
    }

    // MARK: - NSCoding
    required init(coder aDecoder: NSCoder) {
        id = aDecoder.decodeObject(forKey: "id") as? Int ?? aDecoder.decodeInteger(forKey: "id")
        name = aDecoder.decodeObject(forKey: "name") as! String
        URLString = aDecoder.decodeObject(forKey: "URLString") as! String
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(id, forKey: "id")
        aCoder.encode(name, forKey: "name")
        aCoder.encode(URLString, forKey: "URLString")
    }
}

我正在尝试将它的一个实例保存在 UserDefaults 中，但它一直失败并出现以下错误。

由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：“尝试为关键 jobCategory 插入非属性列表对象”

这是我保存在UserDefaults 中的代码。

enum UserDefaultsKeys: String {
    case jobCategory
}

class ViewController: UIViewController {

    @IBAction func didTapSaveButton(_ sender: UIButton) {
        let category = JobCategory(id: 1, name: "Test Category", URLString: "http://www.example-job.com")

        let userDefaults = UserDefaults.standard
        userDefaults.set(category, forKey: UserDefaultsKeys.jobCategory.rawValue)
        userDefaults.synchronize()
    }
}

我将枚举值替换为普通字符串，但仍然出现相同的错误。知道是什么原因造成的吗？

Answer 1

您需要使用archivedData(withRootObject:) 从您的JobCategory 实例创建Data 实例，并将该Data 实例存储在UserDefaults 中，然后使用unarchiveTopLevelObjectWithData(_:) 取消归档，所以试试这样。

用于将数据存储在UserDefaults

let category = JobCategory(id: 1, name: "Test Category", URLString: "http://www.example-job.com")
let encodedData = NSKeyedArchiver.archivedData(withRootObject: category, requiringSecureCoding: false)
let userDefaults = UserDefaults.standard
userDefaults.set(encodedData, forKey: UserDefaultsKeys.jobCategory.rawValue)

用于从UserDefaults检索数据

let decoded  = UserDefaults.standard.object(forKey: UserDefaultsKeys.jobCategory.rawValue) as! Data
let decodedTeams = NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(decoded) as! JobCategory
print(decodedTeams.name)

Answer 2

更新 Swift 4、Xcode 10

我已经围绕它编写了一个结构以便于访问。

//set, get & remove User own profile in cache
struct UserProfileCache {
    static let key = "userProfileCache"
    static func save(_ value: Profile!) {
         UserDefaults.standard.set(try? PropertyListEncoder().encode(value), forKey: key)
    }
    static func get() -> Profile! {
        var userData: Profile!
        if let data = UserDefaults.standard.value(forKey: key) as? Data {
            userData = try? PropertyListDecoder().decode(Profile.self, from: data)
            return userData!
        } else {
            return userData
        }
    }
    static func remove() {
        UserDefaults.standard.removeObject(forKey: key)
    }
}

Profile 是一个 Json 编码的对象。

struct Profile: Codable {
let id: Int!
let firstName: String
let dob: String!
}

用法：

//save details in user defaults...
UserProfileCache.save(profileDetails)

希望对你有帮助！！！

谢谢

Answer 3

将字典保存到用户默认中

let data = NSKeyedArchiver.archivedData(withRootObject: DictionaryData)
UserDefaults.standard.set(data, forKey: kUserData)

检索字典

let outData = UserDefaults.standard.data(forKey: kUserData)
let dict = NSKeyedUnarchiver.unarchiveObject(with: outData!) as! NSDictionary

Answer 4

Swift 将 Codable 对象保存到 UserDefault 和 @propertyWrapper

@propertyWrapper
    struct UserDefault<T: Codable> {
        let key: String
        let defaultValue: T

        init(_ key: String, defaultValue: T) {
            self.key = key
            self.defaultValue = defaultValue
        }

        var wrappedValue: T {
            get {

                if let data = UserDefaults.standard.object(forKey: key) as? Data,
                    let user = try? JSONDecoder().decode(T.self, from: data) {
                    return user

                }

                return  defaultValue
            }
            set {
                if let encoded = try? JSONEncoder().encode(newValue) {
                    UserDefaults.standard.set(encoded, forKey: key)
                }
            }
        }
    }




enum GlobalSettings {

    @UserDefault("user", defaultValue: User(name:"",pass:"")) static var user: User
}

示例用户模型确认可编码

struct User:Codable {
    let name:String
    let pass:String
}

如何使用

//Set value 
 GlobalSettings.user = User(name: "Ahmed", pass: "Ahmed")

//GetValue
print(GlobalSettings.user)

Answer 5

基于Harjot Singh 的回答。我是这样用的：

struct AppData {

    static var myObject: MyObject? {

        get {
            if UserDefaults.standard.object(forKey: "UserLocationKey") != nil {
                if let data = UserDefaults.standard.value(forKey: "UserLocationKey") as? Data {
                    let myObject = try? PropertyListDecoder().decode(MyObject.self, from: data)
                    return myObject!
                }
            }
            return nil
        }

        set {
            UserDefaults.standard.set(try? PropertyListEncoder().encode(newValue), forKey: "UserLocationKey")
        }

    }
}

Answer 6

这是一个 UserDefaults 扩展，用于设置和获取 Codable 对象，如果您将其作为纯文本文件打开，则在 plist（用户默认值）中保持人类可读：

extension Encodable {
    var asDictionary: [String: Any]? {
        guard let data = try? JSONEncoder().encode(self) else { return nil }
        return try? JSONSerialization.jsonObject(with: data) as? [String : Any]
    }
}

extension Decodable {
    init?(dictionary: [String: Any]) {
        guard let data = try? JSONSerialization.data(withJSONObject: dictionary) else { return nil }
        guard let object = try? JSONDecoder().decode(Self.self, from: data) else { return nil }
        self = object
    }
}

extension UserDefaults {
    func setEncodableAsDictionary<T: Encodable>(_ encodable: T, for key: String) {
        self.set(encodable.asDictionary, forKey: key)
    }

    func getDecodableFromDictionary<T: Decodable>(for key: String) -> T? {
        guard let dictionary = self.dictionary(forKey: key) else {
            return nil
        }
        return T(dictionary: dictionary)
    }
}

如果您还想支持（可编码的）数组与 plist 数组之间的往来，请将以下内容添加到扩展中：

extension UserDefaults {
    func setEncodablesAsArrayOfDictionaries<T: Encodable>(_ encodables: Array<T>, for key: String) {
        let arrayOfDictionaries = encodables.map({ $0.asDictionary })
        self.set(arrayOfDictionaries, forKey: key)
    }

    func getDecodablesFromArrayOfDictionaries<T: Decodable>(for key: String) -> [T]? {
        guard let arrayOfDictionaries = self.array(forKey: key) as? [[String: Any]] else {
            return nil
        }
        return arrayOfDictionaries.compactMap({ T(dictionary: $0) })
    }
}

---

如果您不关心 plist 是否可读，可以简单地将其保存为 Data（如果以纯文本形式打开，则看起来像随机字符串）：

extension UserDefaults {
    func setEncodable<T: Encodable>(_ encodable: T, for key: String) throws {
        let data = try PropertyListEncoder().encode(encodable)
        self.set(data, forKey: key)
    }

    func getDecodable<T: Decodable>(for key: String) -> T? {
        guard
            self.object(forKey: key) != nil,
            let data = self.value(forKey: key) as? Data
        else {
            return nil
        }

        let obj = try? PropertyListDecoder().decode(T.self, from: data)
        return obj
    }
}

（使用第二种方法，您不需要顶部的 Encodable 和 Decodable 扩展）