title: How to use Swift extensions in another module?
body: <p>I defined an extension in Swift in my app module and I want to use that extension in another module. Is it possible? I got compiler error "Type 'UserDefaults' has no member 'Keys'" when I used it in another module.</p>
  
  <pre><code>public extension UserDefaults {
      public enum Keys {
          public static let aaa = "aaa"
          public static let bbb = "bbb"
      }
  }
  </code></pre>