         case JPEG70 = "jpg70"
     }
 
-    public var requestURL: NSURL
+    private(set) var requestURL: NSURL
 
     public lazy var image: UIImage? = {
         if let data = NSData(contentsOfURL: self.requestURL) {


    public class Overlay {

        var requestString: String

        init() {
            requestString = ""
        }

    }



public class MapboxStaticMap {

    private let requestURLStringBase = "https://api.tiles.mapbox.com/v4/"

    public enum ImageFormat: String {
        case PNG    = "png"
