How to archive data in swift? - ios

Question

I am trying to archive data and want to store it in userdefault but app getting crash.
Also tried this
let encodedData = try NSKeyedArchiver.archivedData(withRootObject: selectedPoductDetails, requiringSecureCoding: false)
selectedPoductDetails is dict of type [String: SelectedProductDetail]
import Foundation
class SelectedProductDetail {
let product: String
var amount: Double
var title: String
init(product: String, amount: Double, title: String ) {
self.product = product
self.amount = amount
self.title = title
}
}
May i know why its not working and possible solution for same?

Answer 1

For this case you can use UserDefaults
struct ProductDetail: Codable {
//...
}
let encoder = JSONEncoder()
let selectedProductDetails = ProductDetail()
// Set
if let data = try? encoder.encode(selectedProductDetails) {
UserDefaults.standard.set(data, forKey: "selectedProductDetails")
}
// Get
if let selectedProductDetailsData = UserDefaults.standard.object(forKey: "selectedProductDetails") as? Data {
let selectedProductDetails = try? JSONDecoder().decode(ProductDetail.self, from: selectedProductDetailsData)
}

Answer 2

As mentioned in the comments to use NSKeyedArchiver the class must adopt NSSecureCoding and implement the two required methods.
The types in your class are JSON compatible, so adopt Codable and archive the data with JSONEncoder (or PropertyListEncoder). You could even use a struct and delete the init method
struct SelectedProductDetail: Codable {
let product: String
var amount: Double
var title: String
}
var productDetails = [String: SelectedProductDetail]()
// populate the dictionary
do {
let data = try JSONEncoder().encode(productDetails)
UserDefaults.standard.set(data, forKey: "productDetails")
} catch {
print(error)
}
And load it
do {
guard let data = UserDefaults.standard.data(forKey: "productDetails") else { return }
productDetails = try JSONDecoder().decode([String: SelectedProductDetail].self, from: data)
} catch {
print(error)
}
Note:
UserDefaults is the wrong place for user data. It's better to save the data in the Documents folder