Update README.md

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 [![Build Status](https://travis-ci.org/kevinzhow/PNChart.png?branch=master)](https://travis-ci.org/kevinzhow/PNChart)
 
+You can also find swift version at here https://github.com/kevinzhow/PNChart-Swift
+
 A simple and beautiful chart lib with **animation** used in [Piner](https://itunes.apple.com/us/app/piner/id637706410) and [CoinsMan](https://itunes.apple.com/us/app/coinsman/id772163893) for iOS
 
 [![](https://dl.dropboxusercontent.com/u/1599662/pnchart.gif)](https://dl.dropboxusercontent.com/u/1599662/pnchart.gif)