Pinterest do not provide api's for integration yet.
So in order to achieve it we need to use UIWebView in iOS App.
Follow below steps:
1. Take a UIViewController containing two buttons, one UIWebView.
2. Generate HTML programatically and pass it to loadHTMLString in UIWebView.
3. On touchup-inside of first button, load html string which will open Pinterest in UIWebView.
4. Here pass your custom description and image url which you want to pin.
5. On touchup-inside of second button, close/hide the UIWebView.
Download Code from here: PinterestiOSIntegration
http://stackoverflow.com/questions/9909511/ios-application-integration-with-pinterest answer provided by 'wzbozon'
Above link helped me out.