             return objc_getAssociatedObject(self, &BusyNavigationBarLoadingViewAssociationKey) as? UIView
         }
         set(newValue) {
-            objc_setAssociatedObject(self, &BusyNavigationBarLoadingViewAssociationKey, newValue, objc_AssociationPolicy(OBJC_ASSOCIATION_RETAIN))
+            objc_setAssociatedObject(self, &BusyNavigationBarLoadingViewAssociationKey, newValue, .OBJC_ASSOCIATION_RETAIN)
         }
     }
 

        }
    }

    public func start(_ options: BusyNavigationBarOptions? = nil) {
        if let loadingView = self.busy_loadingView {
            loadingView.removeFromSuperview()
        }

    }

    func maskLayer() -> CALayer {
        let alphaLayer = CAGradientLayer()
        alphaLayer.frame = bounds
        alphaLayer.colors = [UIColor(red: 0, green: 0, blue: 0, alpha: 0).CGColor, UIColor(red: 0, green: 0, blue: 0, alpha: 0.2).CGColor]
        return alphaLayer
