Extend 'KeychainWrapper' to store and lookup Dictionaries

Keychain.swift

import Foundation
import SwiftKeychainWrapper

let keychain: KeychainWrapper = KeychainWrapper.standard

/// Add methods that allow a client to save and lookup Dict's.
extension KeychainWrapper {
  func saveDict(_ value: [String: Any], forKey key: String) {
    self.set(NSKeyedArchiver.archivedData(withRootObject: value),
             forKey: key)
  }

  func dict(forKey key: String) -> [String: Any]? {
    if let storedData = self.data(forKey: key) {
      return NSKeyedUnarchiver.unarchiveObject(with: storedData) as? [String: Any]
    }
    return nil
  }
}