     }
     
     /**
-    Set an image with a URL, a place holder image, options and completion handler.
+    Set an image with a URL, a placeholder image, options and completion handler.
     
     :param: URL               The URL of image.
     :param: placeholderImage  A placeholder image when retrieving the image at URL.

    }
    
    /**
    Set an image with a URL, a place holder image, options, progress handler and completion handler.
    
    :param: URL               The URL of image.
    :param: placeholderImage  A placeholder image when retrieving the image at URL.

// MARK: - Associated Object
private var lastURLkey: Void?
public extension UIImageView {
    /// Get the image URL binded to this image view.
    public var kf_webURL: NSURL? {
        get {
            return objc_getAssociatedObject(self, &lastURLkey) as? NSURL
