 
     public class Overlay {
 
-        var requestString: String
-
-        init() {
-            requestString = ""
-        }
+        private(set) var requestString: String = ""
 
     }
 

        case JPEG70 = "jpg70"
    }

    public var requestURL: NSURL

    public lazy var image: UIImage? = {
        if let data = NSData(contentsOfURL: self.requestURL) {


public class MapboxStaticMap {

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

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