                 return point.x } )
         }
         else {
-            labels = xLabels
+            labels = xLabels!
         }
         
         let scaled = scaleValuesOnXAxis(labels)

            }
        }
        else {
            labels = xLabels
        }
        
        let scaled = scaleValuesOnYAxis(labels)

    Values to display as labels of the y-axis. If not specified, will display the
    lowest, the middle and the highest values.
    */
    var yLabels: Array<Float>?
    
    /**
    Formatter for the labels on the y-axis.
