Bdtjtk

I have a class which creates an object ( two strings and one picture of NSData) on the unarchive process, I am getting a pointer. I assume this is where my object lives in memory. Which would be the most appropriate way to unarchive this already saved object from the memory.

This a project I want to make an app which by using an API you can see recipes. I am trying to make another feature where the user can upload their own recipes. since this is my first app ever I am trying to learn about data persistence.

The code seems to work fine, except the part where I need to read unarchive the data from the UserDefaults.

class myRecipes: NSObject, NSCoding {

    var publisher: String

    var image_url: NSData

    var title: String



    enum SerializationError:Error {

        case missing(String)

        case invalid(String, Any)

    }



    init(title: String, publisher: String, image_url: NSData) throws {

        self.publisher = publisher

        self.image_url = image_url

        self.title = title

    }



    required convenience init(coder aDecoder: NSCoder) {

        let publisher = aDecoder.decodeObject(forKey: "publisher") as! String

        let image_url = aDecoder.decodeObject(forKey: "image_url") as! NSData

        let title = aDecoder.decodeObject(forKey: "title") as! String

        try! self.init(title: title, publisher: publisher, image_url: image_url)



    }



    func encode(with aCoder: NSCoder) {

        aCoder.encode(publisher, forKey: "publisher")

        aCoder.encode(image_url, forKey: "image_url")

        aCoder.encode(title, forKey: "title")

    }  

}





func applicationDidEnterBackground(_ application: UIApplication) {



        let userDefaults = UserDefaults.standard

        let encodedData: Data = try! NSKeyedArchiver.archivedData(withRootObject: myRecipess, requiringSecureCoding: false)

        userDefaults.set(encodedData, forKey: "myRecipess")

        userDefaults.synchronize()

    }



    func applicationDidBecomeActive(_ application: UIApplication) {

        // set the notification badge to 0.

        application.applicationIconBadgeNumber = 0



        // decode the use's recipes.

        let userDefaults = UserDefaults.standard

        let decoded  = userDefaults.object(forKey: "myRecipess") as! Data

        let decodedTeams = try! NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(decoded) as! [myRecipes]

        print("decodedTeams")

        print(decodedTeams)

    }

I expect to have the data retrieved from the memory.

In Swift 4 it's highly recommended to use the Codable protocol to archive data.

First of all use a struct and name it in singular form

struct Recipe : Codable {

    var publisher: String

    var imageUrl: Data

    var title: String

}

Then you have a data source array

var recipes = [Recipe]()

To save data write

func applicationDidEnterBackground(_ application: UIApplication) {



    do {

        let encodedData = try PropertyListEncoder().encode(recipes)

        UserDefaults.standard.set(encodedData, forKey: "recipes")

    } catch { print(error) }

}

To load data write

func applicationDidBecomeActive(_ application: UIApplication) {

    // set the notification badge to 0.

    application.applicationIconBadgeNumber = 0



    // decode the use's recipes.

    if let decoded  = UserDefaults.standard.data(forKey: "recipes") {

       do {

          recipes = try PropertyListDecoder().decode([Recipe].self, from: decoded)

          return

       } catch { 

         print(error) 

       }

    }

    recipes = 

}