Storing Set to UserDefaults

Question

I have a custom class which I use as Set<ListItem>. I want to store this to userDefaults. However, I'm getting Attempt to set a non-property-list object as an NSUserDefaults error when trying to. I tried to change it to Array and then save it but still same error. I also tried Saving as data after saw some posts, again this gives me below error.

NSForwarding: warning: object 0x600003bf9a00 of class 'iTunes_Search_Me.ListItem' does not implement methodSignatureForSelector: -- trouble ahead

class ListItem: Codable ,Equatable, Hashable {
    let wrapperType, kind: String?
    let artistID, collectionID, trackID: Int?
    let artistName, collectionName, trackName: String?
    let trackViewURL: String?
    let artworkUrl30, artworkUrl60, artworkUrl100: String?
    let releaseDate: String?
    let primaryGenreName: String?
    var isSelected: Bool = false
    enum CodingKeys: String, CodingKey {
        case wrapperType, kind
        case artistID
        case collectionID
        case trackID
        case artistName, collectionName, trackName
        case trackViewURL
        case artworkUrl30, artworkUrl60, artworkUrl100, releaseDate, primaryGenreName
    }

    static func ==(lhs: ListItem, rhs: ListItem) -> Bool {
        return lhs.trackID == rhs.trackID
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(trackID)
    }
}

Attempt to set a non-property-list object as an NSUserDefaults

It is a less efficient way to solve it. Ex. CoreData. So storing just an array will be a better option but I don't know how to solve this problem. — Emre Önder, Jul 07 '19 at 09:03
What I mean is `UserDefaults` is not meant for storing this kind of data. It's meant for things like user preferences. — Sweeper, Jul 07 '19 at 09:06

emrcftci · Accepted Answer · 2019-11-10T12:32:20.817

You can set the model to UserDefaults like this:

Firstly you should create an instance of your model

And then you can save your model to UserDefaults:

let encoder = JSONEncoder()
if let encoded = try? encoder.encode(listItemInstance) {
    let defaults = UserDefaults.standard
    defaults.set(encoded, forKey: "ListItemObject")
}

You can get model from UserDefaults like this

if let savedItem = defaults.object(forKey: "ListItemObject") as? Data {
    let decoder = JSONDecoder()
    if let loadedItem = try? decoder.decode(ListItem.self, from: savedItem) {
        print(loadedItem)
    }
}

score 0 · Answer 2 · answered Jul 07 '19 at 10:10

0

You could try first setting up saved data:

struct saveData{
   static let encoded = "encoded"
}

Then save it under that key:

UserDefaults.standard.set(encoded as! Data, forKey: "encoded")

or try saving it as a string instead.

answered Jul 07 '19 at 10:10

Hubert Rzeminski

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Storing Set to UserDefaults

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