NSKeyedUnarchiver returning nil when retrieving custom class

Question

In my view controller, I have a custom class store in an array. I was using NSKeyedArchiver to store data but I was using the depreciated version NSKeyedUnarchiver.unarchiveObject(withFile: object.ArchiveURL.path) as? [object].

Now I have decided to update it to: let data = try Data(contentsOf: filePath) let object = try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data)

Here is my save function:

 let data = try NSKeyedArchiver.archivedData(withRootObject: object, requiringSecureCoding: false)
 try data.write(to: filePath)

When I return object from the Unarchiver it returns nil. I'm not sure why. This is my custom class:

class object: NSObject, NSCoding {
   var name: String
   var photo: UIImage

    struct PropertyKey {
        static let name = "name"
        static let photo = "photo"
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(self.name, forKey: PropertyKey.name)
        aCoder.encode(self.photo, forKey: PropertyKey.photo)
    }

    required convenience init?(coder aDecoder: NSCoder) {
         // The name is required. If we cannot decode a name string, the initializer should     fail.
         guard let name = aDecoder.decodeObject(forKey: PropertyKey.name) as? String else {
             os_log("unable to find name", log: OSLog.default, type: .debug)
             return nil
         }

         guard let photo = aDecoder.decodeObject(forKey: PropertyKey.photo) as? UIImage else  {
              os_log("unable to find photo", log: OSLog.default, type: .debug)
              return nil
         }


        // Must call designated initializer.
        self.init(name: name, photo: photo)
   }

   init?(name: String, photo: UIImage) {
        // Initialize stored properties.
        self.name = name
        self.photo = photo

   }
}

Awais · Accepted Answer · 2020-04-08T15:17:30.303

2

You can use this method to unarchive the data. https://developer.apple.com/documentation/foundation/nskeyedunarchiver/2963379-unarchivedobject

NSKeyedUnarchiver.unarchivedObject(ofClasses:from:)

You can write your unarchiving code as;

let data = try Data(contentsOf: filePath)
let object = try NSKeyedUnarchiver.unarchivedObject(ofClasses:[object.self, UIImage.self], from: data)

Hopefully, it works.

PS. One tip about naming classes. They should always start with capital letter.

EDIT: You should add UIImage.self also when trying to unarchive. and you should change your archive method as seen below.

NSKeyedArchiver.archivedData(withRootObject: data, requiringSecureCoding: true)

Your model should also satisfy NSSecureCoding protocol when using this unarchive method.

extension object : NSSecureCoding {
    static var supportsSecureCoding: Bool {
       return true
    }
}

edited Apr 08 '20 at 15:17

answered Apr 07 '20 at 10:17

Awais

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5
13

Would I keep the archive function the same? – ewcrow Apr 07 '20 at 16:30
I have updated my answer. @ewcrow let me know if it still doesn't work for you. – Awais Apr 08 '20 at 15:20
But `try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data)` should also work without satisfying NSSecureCoding protocol. Do you do type casting ? `try NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(data)` as? object – Awais Apr 08 '20 at 15:31

NSKeyedUnarchiver returning nil when retrieving custom class

1 Answers1