 
   /// Moves any pending request for URLString to the front of the download queue.
   ///
-  /// - parameter forURLtring:  The URL string for the request.
+  /// - parameter forURLString:  The URL string for the request.
   public func prioritizeImageRequest(forURLString URLString: String) {
 
     if let foundItem = queuedImageRequest(forURLString: URLString), let index = queuedRequests.index(of: foundItem) {

  case databaseCache
}

public class ImageResponse {
  
  /// The original requested URLString

  
  override var description: String {
    return URLString
  }
}

class ImageMetadata: NSObject, NSCoding {
  
  var created: Date
  var expires: Date?
  
  init(created: Date, expires: Date? = nil) {
    
    self.created = created
    self.expires = expires
  }
  
  func encode(with coder: NSCoder) {
    coder.encode(created, forKey: "created")
    coder.encode(expires, forKey: "expires")
  }
  
  required init?(coder decoder: NSCoder) {
    
    guard
      let created = decoder.decodeObject(forKey: "created") as? Date,
      let expires = decoder.decodeObject(forKey: "expires") as? Date
      else {
        return nil
    }
    self.created = created
    self.expires = expires
  }
}

