Question

我有一个对象数组，每个对象都有许多属性。以下是循环遍历对象数组的一些示例数据：

Name = Rent
Default Value 750
This Months Estimate = 750
Sum Of This Months Actuals = 0
Risk Factor = 0.0
Monthly Average = 750.0
--------------
Name = Bills
Default Value 250
This Months Estimate = 170
Sum Of This Months Actuals = 140
Risk Factor = 0.0
Monthly Average = 190.0
--------------
Name = Food
Default Value 240
This Months Estimate = 200
Sum Of This Months Actuals = 95
Risk Factor = 0.0
Monthly Average = 190.0
--------------
Name = Lunches
Default Value 100
This Months Estimate = 150
Sum Of This Months Actuals = 155
Risk Factor = 0.899999976158142
Monthly Average = 190.0

它的数据很少，所以我想避免使用核心数据。我需要能够持久保存数组然后再次打开它并能够循环它。我希望使用像NSUserDefaults或NSKeyedArchiver这样的简单解决方案，但在Swift中，我既不能使用这种类型的数组（我已经在线阅读文档和论坛和示例24小时了......）

你会如何建议我坚持保存像上面这样的对象数组？或者可能坚持保存这种类型的数组是不好的做法？

提前感谢您的帮助！

添加对象类：

class costCategory : NSObject {
    var name : String
    var defaultValue : Int
    var thisMonthsEstimate : Int
    var sumOfThisMonthsActuals : Int
    var riskFactor : Float
    var monthlyAverage : Float


    init (name:String, defaultValue:Int, thisMonthsEstimate:Int, sumOfThisMonthsActuals:Int, riskFactor:Float, monthlyAverage:Float) {
        self.name = name
        self.defaultValue = defaultValue
        self.thisMonthsEstimate = thisMonthsEstimate
        self.sumOfThisMonthsActuals = sumOfThisMonthsActuals
        self.riskFactor = riskFactor
        self.monthlyAverage = monthlyAverage
    }

}

如果我尝试将数组保存到NSUserDefaults，我收到错误：

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

我尝试过继承NSCoder类，但是我收到了一个无法解决的错误，如下所示：

class costCategory : NSObject, NSCoder {
    var name : String
    var defaultValue : Int
    var thisMonthsEstimate : Int
    var sumOfThisMonthsActuals : Int
    var riskFactor : Float
    var monthlyAverage : Float


    init (name:String, defaultValue:Int, thisMonthsEstimate:Int, sumOfThisMonthsActuals:Int, riskFactor:Float, monthlyAverage:Float) {
        self.name = name
        self.defaultValue = defaultValue
        self.thisMonthsEstimate = thisMonthsEstimate
        self.sumOfThisMonthsActuals = sumOfThisMonthsActuals
        self.riskFactor = riskFactor
        self.monthlyAverage = monthlyAverage
    }



    // MARK: NSCoding

    required convenience init(coder decoder: NSCoder) {
        self.init() //Error here "missing argument for parameter name in call
        self.name = decoder.decodeObjectForKey("name") as String
        self.defaultValue = decoder.decodeIntegerForKey("defaultValue")
        self.thisMonthsEstimate = decoder.decodeIntegerForKey("thisMonthsEstimate")
        self.sumOfThisMonthsActuals = decoder.decodeIntegerForKey("sumOfThisMonthsActuals")
        self.riskFactor = decoder.decodeFloatForKey("riskFactor")
        self.monthlyAverage = decoder.decodeFloatForKey("monthlyAverage")

    }

    func encodeWithCoder(coder: NSCoder) {
        coder.encodeObject(self.name, forKey: "name")
        coder.encodeInt(Int32(self.defaultValue), forKey: "defaultValue")
        coder.encodeInt(Int32(self.thisMonthsEstimate), forKey: "thisMonthsEstimate")
        coder.encodeInt(Int32(self.sumOfThisMonthsActuals), forKey: "sumOfThisMonthsActuals")
        coder.encodeFloat(self.riskFactor, forKey: "riskFactor")
        coder.encodeFloat(self.monthlyAverage, forKey: "monthlyAverage")

    }
}

Answer 1

一种可能性是将对象属性：value转换为string：object将它们存储到NSUserDefaults然后获取并解码它们。

如果您想使用NSKeyedArchiver存储对象，那么您的类需要符合NSCoding并且是NSObject的子类。例如：

class costCategory : NSObject, NSCoding {
    var name : String
    var defaultValue : Int
    var thisMonthsEstimate : Int
    var sumOfThisMonthsActuals : Int
    var riskFactor : Float
    var monthlyAverage : Float

    init (name:String, defaultValue:Int, thisMonthsEstimate:Int, sumOfThisMonthsActuals:Int, riskFactor:Float, monthlyAverage:Float) {
        self.name = name
        self.defaultValue = defaultValue
        self.thisMonthsEstimate = thisMonthsEstimate
        self.sumOfThisMonthsActuals = sumOfThisMonthsActuals
        self.riskFactor = riskFactor
        self.monthlyAverage = monthlyAverage
    }

    // MARK: NSCoding

    required init(coder decoder: NSCoder) {
        //Error here "missing argument for parameter name in call
        self.name = decoder.decodeObjectForKey("name") as String
        self.defaultValue = decoder.decodeIntegerForKey("defaultValue")
        self.thisMonthsEstimate = decoder.decodeIntegerForKey("thisMonthsEstimate")
        self.sumOfThisMonthsActuals = decoder.decodeIntegerForKey("sumOfThisMonthsActuals")
        self.riskFactor = decoder.decodeFloatForKey("riskFactor")
        self.monthlyAverage = decoder.decodeFloatForKey("monthlyAverage")
        super.init()
    }

    func encodeWithCoder(coder: NSCoder) {
        coder.encodeObject(self.name, forKey: "name")
        coder.encodeInt(Int32(self.defaultValue), forKey: "defaultValue")
        coder.encodeInt(Int32(self.thisMonthsEstimate), forKey: "thisMonthsEstimate")
        coder.encodeInt(Int32(self.sumOfThisMonthsActuals), forKey: "sumOfThisMonthsActuals")
        coder.encodeFloat(self.riskFactor, forKey: "riskFactor")
        coder.encodeFloat(self.monthlyAverage, forKey: "monthlyAverage")

    }
}

然后您可以存档并保存到NSDefaults：

let defaults = NSUserDefaults.standardUserDefaults()
let arrayOfObjectsKey = "arrayOfObjectsKey"

var arrayOfObjects = [costCategory]()
var arrayOfObjectsData = NSKeyedArchiver.archivedDataWithRootObject(arrayOfObjects)

defaults.setObject(arrayOfObjectsData, forKey: arrayOfObjectsKey)

// ...

var arrayOfObjectsUnarchivedData = defaults.dataForKey(arrayOfObjectsKey)!
var arrayOfObjectsUnarchived = NSKeyedUnarchiver.unarchiveObjectWithData(arrayOfObjectsUnarchivedData) as [costCategory]

Answer 2

核心数据非常强大，我强烈建议您不要被其令人生畏的外观所左右。当您的应用程序增长时，您会非常感激您使用Core Data支持您的数据，因为它的扩展性非常好。

话虽如此，这是一篇关于NSHipster that covers the basics of using the NSKeyedArchiver的好文章。所以解决方案是让你的对象成为NSObject的子类并符合NSCoding协议。这允许您归档从磁盘中取消归档对象。您可以将文件保存到documents directory

然后你的子类需要隐式解包所有可编码的变量，结果会产生：

class costCategory : NSObject, NSCoding {
var name : String!
var defaultValue : Int!
var thisMonthsEstimate : Int!
var sumOfThisMonthsActuals : Int!
var riskFactor : Float!
var monthlyAverage : Float!


init (name:String, defaultValue:Int, thisMonthsEstimate:Int, sumOfThisMonthsActuals:Int, riskFactor:Float, monthlyAverage:Float) {
    self.name = name
    self.defaultValue = defaultValue
    self.thisMonthsEstimate = thisMonthsEstimate
    self.sumOfThisMonthsActuals = sumOfThisMonthsActuals
    self.riskFactor = riskFactor
    self.monthlyAverage = monthlyAverage
}

override init() {
    super.init()
}

// MARK: NSCoding

required convenience init(coder decoder: NSCoder) {
    self.init()
    self.name = decoder.decodeObjectForKey("name") as String
    self.defaultValue = decoder.decodeIntegerForKey("defaultValue")
    self.thisMonthsEstimate = decoder.decodeIntegerForKey("thisMonthsEstimate")
    self.sumOfThisMonthsActuals = decoder.decodeIntegerForKey("sumOfThisMonthsActuals")
    self.riskFactor = decoder.decodeFloatForKey("riskFactor")
    self.monthlyAverage = decoder.decodeFloatForKey("monthlyAverage")
}

func encodeWithCoder(coder: NSCoder) {
    coder.encodeObject(self.name, forKey: "name")
    coder.encodeInteger((self.defaultValue), forKey: "defaultValue")
    coder.encodeInteger((self.thisMonthsEstimate), forKey: "thisMonthsEstimate")
    coder.encodeInteger((self.sumOfThisMonthsActuals), forKey: "sumOfThisMonthsActuals")
    coder.encodeFloat(self.riskFactor, forKey: "riskFactor")
    coder.encodeFloat(self.monthlyAverage, forKey: "monthlyAverage")
}
}

然后，您可以添加一种在文档目录中查找位置的方法：

func documentsDirectory() -> NSString {
    let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
    let documentDirectory = paths[0] as String
    return documentDirectory
}

所以存档看起来像这样：

var filePath = documentsDirectory().stringByAppendingPathComponent("fileName")
NSKeyedArchiver.archiveRootObject(receipts, toFile: filePath)

以后你可以从磁盘读回你的数组：

let receipts = NSKeyedUnarchiver.unarchiveObjectWithFile(filePath)

我建议不要使用User Defaults来存储数组，它的意思是存储首选项，这里看看文档：

NSUserDefaults类为其提供编程接口与默认系统交互。默认系统允许应用程序以自定义其行为以匹配用户的首选项。例如，您可以允许用户确定哪些单位测量您的应用程序显示或文档的频率自动保存。应用程序通过分配记录此类首选项值为用户默认数据库中的一组参数。

理想情况下，您不希望持久化数组，因为即使您需要一个对象，也必须将整个数组提取到内存中。自然核心数据将为您解决所有不必要的堆混乱:)

修改

为了让自己更容易进入核心数据，您可以随时查看Magical Record。它们简化了维护Core Data堆栈所需的大量工作。

祝你好运

核心数据传播者

Swift中的简单持久存储

2 个答案: