Array of structs: UserDefaults, how to use?

Question

I've already check all of those topics:

How to save an array of custom struct to NSUserDefault with swift?

How to save struct to NSUserDefaults in Swift 2.0

STRUCT Array To UserDefaults

I have a struct containing some Strings and an other struct: MySection.

struct MySection {
  var name: String = ""
  var values: [MyRow] = []
}

And there is MyRow which is store in MySection.values

struct MyRow {
  var value: String = ""
  var quantity: String = ""
  var quantityType: String = ""
  var done: String = ""
}

Two arrays for use it

var arraySection: [MySection] = []
var arrayRow: [MyRow] = []

And in my application, I add dynamically some values in those arrays.

There is the delegate method for get datas from my second ViewController

func returnInfos(newItem: [MyRow], sectionPick: String) {
    arrayRow.append(MyRow())
    arrayRow[arrayRow.count - 1] = newItem[0]
    manageSection(item: sectionPick)
    listTableView.reloadData()
}

And there is the manageSection function.

func manageSection(item: String) {
    var i = 0
    for _ in arraySection {
        if arraySection[i].name == item {
            arraySection.insert(MySection(), at: i + 1)
            arraySection[i + 1].values = [arrayRow[arrayRow.count - 1]]
            return
        }
        i += 1
    }
    arraySection.append(MySection())
    arraySection[arraySection.count - 1].name = item
    arraySection[arraySection.count - 1].values = [arrayRow[arrayRow.count - 1]]
}

My need is to store datas of the two arrays in UserDefaults (or CoreData maybe??) and use these datas when the user going back to the application.

I don't know how to do it, I've already try methods from the 3 topics but I'm not even doing a good job.

How can I do it?

Thanks guys!

Answer 1

Since both types contain only property list compliant types a suitable solution is to add code to convert each type to a property list compliant object and vice versa.

struct MySection {
    var name: String
    var values = [MyRow]()

    init(name : String, values : [MyRow] = []) {
        self.name = name
        self.values = values
    }

    init(propertyList: [String: Any]) {
        self.name = propertyList["name"] as! String
        self.values = (propertyList["values"] as! [[String:String]]).map{ MyRow(propertyList: $0) }
    }

    var propertyListRepresentation : [String: Any] {
        return ["name" : name, "values" : values.map { $0.propertyListRepresentation }]
    }
}

struct MyRow {
    var value: String
    var quantity: String
    var quantityType: String
    var done: String

    init(value : String, quantity: String, quantityType: String, done: String) {
        self.value = value
        self.quantity = quantity
        self.quantityType = quantityType
        self.done = done
    }

    init(propertyList: [String:String]) {
        self.value = propertyList["value"]!
        self.quantity = propertyList["quantity"]!
        self.quantityType = propertyList["quantityType"]!
        self.done = propertyList["done"]!
    }

    var propertyListRepresentation : [String: Any] {
        return ["value" : value, "quantity" : quantity,  "quantityType" : quantityType, "done" : done ]
    }
}

After creating a few objects

let row1 = MyRow(value: "Foo", quantity: "10", quantityType: "Foo", done: "Yes")
let row2 = MyRow(value: "Bar", quantity: "10", quantityType: "Bar", done: "No")

let section = MySection(name: "Baz", values: [row1, row2])

call propertyListRepresentation to get a dictionary ([String:Any]) which can be saved to User Defaults.

let propertyList = section.propertyListRepresentation

Recreation of the section is quite easy, too

let newSection = MySection(propertyList: propertyList)

---

Edit

Use the propertyList initializer only if you get data from UserDefaults in all other cases use the other initializer.

For example replace

@IBAction func addButtonPressed(_ sender: Any) {
    newProducts.append(MyRow(propertyList: ["":""]))
    newProducts[newProducts.count - 1].value = nameTextField.text!
    newProducts[newProducts.count - 1].quantity = quantityTextField.text!
    newProducts[newProducts.count - 1].quantityType = type
    newProducts[newProducts.count - 1].done = "No"
    delegate?.returnInfos(newItem: newProducts, sectionPick: typePick)
    navigationController?.popViewController(animated: true)
}

with

@IBAction func addButtonPressed(_ sender: Any) {

    let row = MyRow(value: nameTextField.text!,
                    quantity: quantityTextField.text!,
                    quantityType: type,
                    done: "No")
    newProducts.append(row)
    delegate?.returnInfos(newItem: newProducts, sectionPick: typePick)
    navigationController?.popViewController(animated: true)
}

and replace

func returnInfos(newItem: [MyRow], sectionPick: String) {
    arrayRow.append(MyRow(propertyList: ["":""]))
    arrayRow[arrayRow.count - 1] = newItem[0]
    manageSection(item: sectionPick)
    listTableView.reloadData()
}

with

func returnInfos(newItem: [MyRow], sectionPick: String) {
    arrayRow.append(newItem[0])
    manageSection(item: sectionPick)
    listTableView.reloadData()
}

Basically first create the object, then append it to the array. The other way round is very cumbersome.