Ios 符合NSCoding的类

我将以下

Person

课程符合

NSCoding

协议

class Person: NSObject, NSCoding{

    var age:Int
    var height: Double
    var name: String

    init(age:Int, height: Double, name:String){
        self.age = age
        self.height = height
        self.name = name
    }

    func encode(with aCoder: NSCoder){
        aCoder.encode(age, forKey: "age")
        aCoder.encode(height, forKey: "height")
        aCoder.encode(name, forKey: "name")
    }

    required init?(coder aDecoder: NSCoder){
        age = aDecoder.decodeObject(forKey: "age") as! Int **//error**
        height = aDecoder.decodeObject(forKey: "height") as! Double
        name = aDecoder.decodeObject(forKey: "name") as! String
        super.init()
    }


}

然后，我创建了这个类的一个数组。我使用

NSKeyedArchiver

将其归档到plist，一切正常。然而，当我试图取消归档时，我得到了一个错误，它涉及到打开一个可选文件，该文件为零。错误出现在标记的

Person

类中。这是我使用的代码：

 if let people = unarchive(){
            print(people)
 }

以下是取消归档的函数：

func unarchive()->[Person]?{
    let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentDirectory = paths[0]
    let path = documentDirectory.appending("ObjectData.plist")
    let fileManager = FileManager.default
    if(!fileManager.fileExists(atPath: path)){
        if let bundlePath = Bundle.main.path(forResource: "ObjectData", ofType: "plist"){
            do{
                try fileManager.copyItem(atPath: bundlePath, toPath: path)
            }catch{
                print("problem copying")
            }
        }
    }
    if let objects = NSKeyedUnarchiver.unarchiveObject(withFile: path){
        if let people = objects as? [Person]{
            return people
        }else{
            return nil
        }
    }else{
        return nil
    }
}

---

Int

和

Double

不作为对象存档

aDecoder.decodeObject（forKey:）

对于它们将始终返回

nil

，并使用

作为为
nil
将使你的应用程序崩溃

因此，请使用以下方法：

aDecoder.decodeInteger(forKey: "age")
aDecoder.decodeDouble(forKey: "height")

对于
name
字段，您可以保留您的代码。
Int
和
Double
不作为对象存档
aDecoder.decodeObject（forKey:）
对于它们将始终返回
nil
，并使用
作为为
nil
将使你的应用程序崩溃

因此，请使用以下方法：

aDecoder.decodeInteger(forKey: "age")
aDecoder.decodeDouble(forKey: "height")

对于
name
字段，您可以保留您的代码。
您应该使用正确的Int和Double解码方法。您可以在操场中粘贴以下代码并对其进行测试：

import Foundation

class Person: NSObject, NSCoding{

    var age:Int
    var height: Double
    var name: String

    init(age:Int, height: Double, name:String){
        self.age = age
        self.height = height
        self.name = name
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(age, forKey: "age")
        aCoder.encode(height, forKey: "height")
        aCoder.encode(name, forKey: "name")
    }

    required init?(coder aDecoder: NSCoder) {
        age = aDecoder.decodeInteger(forKey: "age")
        height = aDecoder.decodeDouble(forKey: "height")
        name = aDecoder.decodeObject(forKey: "name") as! String
        super.init()
    }
}

let john = Person(age: 30, height: 170, name: "John")
let mary = Person(age: 25, height: 140, name: "Mary")

let guys = [john, mary]

let data = NSKeyedArchiver.archivedData(withRootObject: guys)
let people = NSKeyedUnarchiver.unarchiveObject(with: data)

dump (people)

对于Int和Double，应该使用正确的解码方法。您可以在操场中粘贴以下代码并对其进行测试：

import Foundation

class Person: NSObject, NSCoding{

    var age:Int
    var height: Double
    var name: String

    init(age:Int, height: Double, name:String){
        self.age = age
        self.height = height
        self.name = name
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(age, forKey: "age")
        aCoder.encode(height, forKey: "height")
        aCoder.encode(name, forKey: "name")
    }

    required init?(coder aDecoder: NSCoder) {
        age = aDecoder.decodeInteger(forKey: "age")
        height = aDecoder.decodeDouble(forKey: "height")
        name = aDecoder.decodeObject(forKey: "name") as! String
        super.init()
    }
}

let john = Person(age: 30, height: 170, name: "John")
let mary = Person(age: 25, height: 140, name: "Mary")

let guys = [john, mary]

let data = NSKeyedArchiver.archivedData(withRootObject: guys)
let people = NSKeyedUnarchiver.unarchiveObject(with: data)

dump (people)