将结构数组保存到userDefaults

Question

In my app I have the user take a picture of an item of clothing, then give it a tag describing what type it is (pants, shirt, shoes, etc). I then take this info and save it into a struct Item. After that, I put the recently made Item into an array of Items. I'm struggling with how to save this array of Items to UserDefaults so I can load back when the app is closed.

I've tried adding Codable to my struct but that just brought up more issues. I wanted to update the UserDefaults every time the user adds a new item to the array. I plan to do it in saveItemButton function (shown below).

var itemsArray: [Item] = []

//.pants, .shirt, .shoes, .hat, .extra, .jacket
var itemType: clothingType? = nil

@IBAction func saveItemButton(_ sender: Any) {
    if(itemType != nil && imageView.image != nil){
        saveImage(imageName: ("item" + "\(itemsArray.count)"))
        let item = Item(itemType: itemType!, itemName: ("item" + "\(itemsArray.count)"))


        itemsArray.append(item)

        //let defaults = UserDefaults.standard
        //defaults.set(itemsArray, forKey: "SavedItemArray")
    }
}

Here is my struct in a separate swift file:

import Foundation
import UIKit


struct Item{
    var itemType: clothingType
    var itemName: String
    //var itemImage: UIImage?
}

enum clothingType{
    case pants
    case shirt
    case jacket
    case shoes
    case hat
    case extra
}

And here is where I would load the itemArray from UserDefaults:

override func viewDidLoad() {
    super.viewDidLoad()
    //        let defaults = UserDefaults.standard
    //        let array = defaults.array(forKey: "SavedItemArray")  as? [Item] ?? [Item]()
    //        itemsArray = array
}

Looking to be able to save and load an array of Item to UserDefaults.

Answer 1

Like this:

struct Item : Codable {
    var itemType: clothingType
    var itemName: String
}

enum clothingType : String, Codable {
    case pants
    case shirt
    case jacket
    case shoes
    case hat
    case extra
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let defaults = UserDefaults.standard
        if let data = defaults.data(forKey: "SavedItemArray") {
            let array = try! PropertyListDecoder().decode([Item].self, from: data)
        }
    }
}

Of course I suppose now you're wondering how we got the data into user defaults in the first place. Like this:

    let array : [Item] = // whatever
    if let data = try? PropertyListEncoder().encode(array) {
        UserDefaults.standard.set(data, forKey: "SavedItemArray")
    }

Answer 2

As @rmaddy comment says

Saving those kind of data into the UserDefault is not recommended

however technically let's say you're going to save those however you like, UserDefault don't accept this type of structure, what you need to do is converting this array to type Data saving it into the UserDefault then fetch it as Data then cast it back to it's original form, but again this is not recommended.

Read more about it here .

Also hitting search on this

what is user defaults for swift ?

Will give you the answer of this

The user defaults is a .plist file in your app's package and you can use it to set and get simple pieces of data . It's structure is very similar to that of a dictionary and the user defaults are often regarded as a key-value store .