swift NSPredicate Data (Struct) - swift

Question

In realm i saving struct data like this
class DBDialogs: Object {
#objc dynamic var userId = 0
#objc dynamic var initials = ""
#objc private dynamic var structData:Data? = nil
var Info : User? {
get {
if let data = structData {
do {
return try JSONDecoder().decode(User.self, from: data)
}catch {
return nil
}
}
return nil
}
set {
structData = try? JSONEncoder().encode(newValue)
}
}
}
struct User : Codable {
var pk : Int?
var email : String?
var brand : String?
var discs : Discs?
enum CodingKeys: String, CodingKey {
case pk = "pk"
case email = "email"
case brand = "brand"
case discs = "discs"
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
pk = try values.decodeIfPresent(Int.self, forKey: .pk)
email = try values.decodeIfPresent(String.self, forKey: .email)
brand = try values.decodeIfPresent(String.self, forKey: .brand)
discs = try values.decodeIfPresent(Discs.self, forKey: .discs)
}
}
how can i filter the struct data ? trying something like this, but i get the error (Unable to parse the format string "Info?.brand == %#")
var dbDialogsArray: Results<DBDialogs>?
var dbDialogsMethods = DBDialogsMethods()
....
class DBDialogsMethods { // also in this class i will write to realm, update, delete and etc
var realm: Realm!
func getArray() -> Results<DBDialogs> {
return realm.objects(DBDialogs.self)
}
}
....
let realm = try! Realm()
dbDialogsMethods.realm = realm
dbDialogsArray = dbDialogsMethods.getArray()
...
let predicate = NSPredicate(format: "Info?.brand = %#", brandField.text!)
let filteredDialogs = dbDialogsArray?.filter(predicate)
i have array DBDialogs, i need to filter the array by fields in Info (structData)
Why i do with NSPredicate :
I have several fields by which I filter data (fields for filtering are selected manually in the application), using NSPredicate I can filter multiple fields that the user chose in the app, something like this
var stringPredicate = Dictionary <String, NSObject> ()
stringPredicate ["brand"] = brand.text! as NSObject
var generalPredicates = [NSPredicate] ()
        for (key, value) in stringPredicate {
            let predicate = NSPredicate (format: "% K =% #", key, value)
            generalPredicates.append (predicate)
        }
and filter everything at once, I don’t know how to do filtering in another way with the condition that you need to filter only those fields that the user selected in the application