Open maps iphone app from my app, with pin drop at the coordinate

I'm using http://maps.google.com.au/?ll=, to open maps iPhone app from my app, but it only s开发者_如何学Chow the coordinate without the pin drop automatically. How can i make the pin to drop automatically?

You are required to pass lat-long by appending into the URL like following way - http://maps.google.com/?q=37.342,-122.434