Added convenience method for grayscale

Author: jonhull

GradientSlider.xcodeproj/project.xcworkspace/xcuserdata/jon.xcuserdatad/UserInterfaceState.xcuserstate

@@ -168,6 +168,12 @@ import UIKit
         maxColor = UIColor(red: red, green: green, blue: 1.0, alpha: 1.0)
     }
 
+    func setGradientForGrayscale(){
+        hasRainbow = false
+        minColor = UIColor.blackColor()
+        maxColor = UIColor.whiteColor()
+    }
+    
 
     //MARK: - Private Properties
 

GradientSlider/GradientSlider.swift

@@ -47,20 +47,23 @@ When the `hasRainbow` property is set to true, the track displays a rainbow grad
 ### Convenience Methods
 Since one of the primary uses of the gradient sliders is to create color pickers, a few convenience methods have been provided for updating the colors.
 
-#### HSB
+**HSB**
 `setGradientForHueWithSaturation(saturation:CGFloat,brightness:CGFloat)` This method sets the track to a rainbow gradient with the given saturation and brightness. This is useful for choosing a hue in the context of the current saturation and brightness settings.
 
 `setGradientForSaturationWithHue(hue:CGFloat,brightness:CGFloat)` This method sets the track to a gradient varying from grey to fully saturated with the hue and brightness provided. This is useful for choosing a saturation value in the context of the current hue and brightness settings.
 
 `setGradientForBrightnessWithHue(hue:CGFloat,saturation:CGFloat)` This method sets the track to a gradient varying from black to full brightness with the hue and saturation provided. This is useful for choosing a brightness value in the context of the current hue and saturation settings.
 
-#### RGB
+**RGB**
 `setGradientForRedWithGreen(green:CGFloat, blue:CGFloat)` This method sets the track to a gradient with varying red for the given green & blue values.
 
 `setGradientForGreenWithRed(red:CGFloat, blue:CGFloat)` This method sets the track to a gradient with varying green for the given red & blue values.
 
 `setGradientForBlueWithRed(red:CGFloat, green:CGFloat)` This method sets the track to a gradient with varying blue for the given red & green values.
 
+**Grayscale**
+`setGradientForGrayscale()` This method sets the track to a gradient from black to white.
+
 ## Responding to User Interaction
 ### Target/Action
 As a UIControl subclass, the traditional target/action approach is fully supported. The slider will send TouchDown, ValueChanged, and TouchUpInside actions. If the `continuous` property is set to true (which it is by default), then the slider will send ValueChanged actions as the slider changes, otherwise a ValueChanged action is only sent when the user releases the slider.