如何在用户默认中保存对象列表？

Question

我的目标是：

 struct Order: Codable {
        var item_id:String = ""
        var quantity:Int = 0
        var image:String = ""
        var name:String = ""
        var desc:String = ""
    }

函数的class是：

    class func saveOrder(value: [Order]) {
        print(value)
        let placesData = NSKeyedArchiver.archivedData(withRootObject: value)
        UserDefaults.standard.set(placesData, forKey: "orderHistoryArray")
    }

    class func getOrder() -> [Order] {
        if let order = UserDefaults.standard.array(forKey: "orderHistoryArray") {
            return order as! [Order]
        }
        return []
    }

当我尝试使用这个功能时:

            SavedData.saveOrder(value: itemsInCart)

它不适合我，有什么帮助吗？！！！

Answer 1

如果您实施 Codable 则使用

do {
     let data = try JSONEncoder().encode(arr)
     // save data here 

     // to load
     let data = //// get it here 
     let arr = try JSONDecoder().decode([Order].self, from: data)
           
   }
   catch {
     print(error)
   }

Answer 2

要使您的 NSKeyedArchiver.archivedData(withRootObject: value) 正常工作，您的 Order 需要符合 Codable 协议。只需将这些添加到您的 Order 结构中，它就可以正常工作。

required public init(coder decoder: NSCoder) {

    item_id = decoder.decodeObject(forKey: "item_id") as? String ?? ""
    quantity = decoder.decodeObject(forKey: "quantity") as? Int ?? 0
    image = decoder.decodeObject(forKey: "image") as? String ?? ""
    name = decoder.decodeObject(forKey: "name") as? String ?? ""
    desc = decoder.decodeObject(forKey: "desc") as? String ?? ""

}

public func encode(with coder: NSCoder) {

    coder.encode(item_id, forKey: "item_id")
    coder.encode(quantity, forKey: "quantity")
    coder.encode(image, forKey: "image")
    coder.encode(name, forKey: "name")
    coder.encode(desc, forKey: "desc")
}

Answer 3

可编码

您可以使用 Codable 保存和加载数组 to/from UserDefaults。

节省

这就是您保存它的方式

class func saveOrders(_ orders: [Order]) {
    guard let data = try? JSONEncoder().encode(orders) else { return }
    UserDefaults.standard.set(data, forKey: "orders")
}

加载中

这就是您加载它的方式

class func loadOrders() -> [Order] {
    guard
        let data = UserDefaults.standard.data(forKey: "orders"),
        let orders = try? JSONDecoder().decode([Order].self, from: data)
    else { return [] }
    return orders
}

Answer 4

您混淆了协议 Codable 和 NSCoding

1) NSCoding

NSKeyed(Un)Archiver 属于 NSCoding。要使用它，您必须将 Order 声明为 class 继承自 NSObject 并采用协议及其所需的方法

class Order: NSObject, NSCoding {
    var item_id : String // no need to assign default values
    var quantity : Int
    var image : String
    var name : String
    var desc : String

    required init(coder decoder: NSCoder) 
    {
        item_id = decoder.decodeObject(forKey: "item_id") as! String
        quantity = decoder.decodeInteger(forKey: "quantity")
        image = decoder.decodeObject(forKey: "image") as! String
        name = decoder.decodeObject(forKey: "name") as! String
        desc = decoder.decodeObject(forKey: "desc") as! String
    }

    func encode(with coder: NSCoder) 
    { 
        coder.encode(item_id, forKey: "item_id")
        coder.encode(quantity, forKey: "quantity")
        coder.encode(image, forKey: "image")
        coder.encode(name, forKey: "name")
        coder.encode(desc, forKey: "desc")
    }
}

然后就可以加载和保存数据了

class func saveOrder(value: [Order]) {
    print(value)
    let placesData = NSKeyedArchiver.archivedData(withRootObject: value)
    UserDefaults.standard.set(placesData, forKey: "orderHistoryArray")
}

class func getOrder() -> [Order] {
    guard let orderData = UserDefaults.standard.data(forKey: "orderHistoryArray"),
          let order = NSKeyedUnarchiver.unarchiveObject(with: orderData) as? [Order] else { return [] }
    return order
}

2) 可编码

使用 Codable 你可以保留你的结构。只要采用协议，将编码器创建的Data保存到磁盘

struct Order : Codable {
    var item_id : String
    var quantity : Int
    var image : String
    var name : String
    var desc : String
}

// Both methods `throw` to hand over an en-/decoding error to the caller
class func saveOrder(value: [Order]) throws {
    print(value)
    let placesData = try JSONEncoder().encode(value) else { return }
    UserDefaults.standard.set(placesData, forKey: "orderHistoryArray")
}

class func getOrder() throws -> [Order] {
    guard let orderData = UserDefaults.standard.data(forKey: "orderHistoryArray") else { return [] }
    return try JSONDecoder().decode([Order].self, from: orderData)
}

Answer 5

您可以只使用属性列表编码器和属性列表解码器将您的模型保存为用户默认值。很简单：

假设您有一个订单类型的模型，

class func saveOrder(value: [Order]) {
    PropertyListEncoder().encode(value), forKey: "Somekey")
}

class func getOrder() -> [Order]? {
    if let data = UserDefaults.standard.value(forKey: "Somekey") as? Data {
        let orderDetail = try? PropertyListDecoder().decode([Order].self, from: data)
        return orderDetail!
    } else {
        return nil
    }
}

一般例子

假设您使用 Json 解码器像这样解码一些数据：

let decodedValue = try JSONDecoder().decode(Order.self, from: data)

或

let decodedValue : Order = Order(a: 1, b: 0) // your order model value type,

// 现在您可以轻松地将解码后的模型对象保存到用户默认值

do {
      UserDefaults.standard.set(try PropertyListEncoder().encode(decodedValue), forKey: "Some key")
} catch let err {
      print(err)
}

Answer 6

我用这个 class 来解决这个问题 :

class Order: NSObject, NSCoding {


var item_id:String = ""
var quantity:String = ""
var image:String = ""
var name:String = ""
var desc:String = ""

init(item_id: String ,quantity : String , image : String , name: String, desc: String){
    self.item_id = item_id
    self.quantity = quantity
    self.image = image
    self.name = name
    self.desc = desc
}

func encode(with aCoder: NSCoder) {
    aCoder.encode(item_id, forKey: "item_id")
    aCoder.encode(quantity, forKey: "quantity")
    aCoder.encode(image, forKey: "image")
    aCoder.encode(name, forKey: "name")
    aCoder.encode(desc, forKey: "desc")
}

required init?(coder aDecoder: NSCoder) {
    self.item_id = aDecoder.decodeObject(forKey: "item_id") as! String
    self.quantity = aDecoder.decodeObject(forKey: "quantity") as! String
    self.image = aDecoder.decodeObject(forKey: "image") as! String
    self.name = aDecoder.decodeObject(forKey: "name") as! String
    self.desc = aDecoder.decodeObject(forKey: "desc") as! String
}
}

那我就用这个函数来用

class func save(value : Order){
    var orderArray:[Order] = retrive()
    orderArray.append(value)
    let orderArrayAchived = NSKeyedArchiver.archivedData(withRootObject: orderArray)
    UserDefaults.standard.set(orderArrayAchived, forKey: "orderArray")
}

class func saveListOfOrder(value: [Order]) {
    print(value)
    let cartArrayAchived = NSKeyedArchiver.archivedData(withRootObject: value)
    UserDefaults.standard.set(cartArrayAchived, forKey: "orderArray")
}

class func retrive()-> [Order]{
    let orderData = UserDefaults.standard.object(forKey: "orderArray") as? NSData
    if orderData == nil
    {
        return [Order]()
    }
    let orderArray = NSKeyedUnarchiver.unarchiveObject(with: orderData! as Data) as? [Order]
    return orderArray!
}

如何在用户默认中保存对象列表？

How to save list of object in user Default?

ios

arrays

swift

list

nsuserdefaults

可编码

节省

加载中