如何在快速代码中保存一组类

Question

我正在尝试保存一个类数组，这是我目前的代码：

数组：

var person1 = person(name: "Bob", age: 22)
var person2 = person(name: "John", age: 10)
var array = [person1, person2]

自定义类：

import UIKit

class person: NSObject, NSCoding {

    var name : String
    var age : Int

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

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

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

保存数组：

let SavedData = NSKeyedArchiver.archivedData(withRootObject: array)

let defaults = UserDefaults.standard

defaults.set(SavedData, forKey: "myPeople")

加载数组：

let saveddata = UserDefaults.standard.object(forKey: "myPeople") as? Data

if saveddata != nil{
    array = (NSKeyedUnarchiver.unarchiveObject(with: saveddata!) as? [person])!
}

错误在age = (aDecoder.decodeObject(forKey: "age") as? Int)!这一行

Interface Builder 文件中的未知类 iewripple。

Answer 1

发生错误是因为您正在编码 Int 但解码 object 失败。

有一个专门的方法decodeInteger(forKey。

请遵守类名以大写字母开头，变量名以小写字母开头的命名约定。

class Person: NSObject, NSCoding {

为解决问题，将init(coder方法改为

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

强制解包字符串是 100% 安全的，因为该值始终被编码为非可选。

---

保存数组

let savedData = NSKeyedArchiver.archivedData(withRootObject: array)
UserDefaults.standard.set(savedData, forKey: "myPeople")

加载数组

if let savedData = UserDefaults.standard.object(forKey: "myPeople") as? Data {
    array = NSKeyedUnarchiver.unarchiveObject(with: savedData) as! [Person]
}

如果可选绑定 as? Data 成功，在这种情况下强制解包也是安全的。

Answer 2

您不应该强制展开。尝试获取

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

替换为

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

获取

let saveddata = UserDefaults.standard.object(forKey: "myPeople") as? Data
if saveddata != nil{
    array = (NSKeyedUnarchiver.unarchiveObject(with: saveddata!) as? [person])!
}

替换为

if let data = UserDefaults.standard.object(forKey: "myPeople"),
    let array = NSKeyedUnarchiver.unarchiveObject(with: data as! Data) as? [person] {
    persons = array
}

我已经测试过了。代码工作正常。

let person1 = person(name: "Bob", age: 22)
let person2 = person(name: "John", age: 10)
var persons = [person1, person2]

// Save data
let data = NSKeyedArchiver.archivedData(withRootObject: persons)
let defaults = UserDefaults.standard
defaults.set(data, forKey: "myPeople")

// Load data
if let data = UserDefaults.standard.object(forKey: "myPeople"),
    let array = NSKeyedUnarchiver.unarchiveObject(with: data as! Data) as? [person] {
    persons = array
}

此外，习惯上将类名的第一个字母大写。您可以查看this 以了解命名约定。