<p>I would like to create an iPhone app that can open the google maps app and place a pin on the map.</p>

<p>I have the exact location of the pin, specified by its longitude and latitude.
I also have a name for the pin e.g. 'location 1' that should be displayed along with the pin.</p>

<p>I know that UIApplication:openURL can be used for this but I don't know the exact url format.</p>

<p>So, is there a way to do what I described above? If, yes, what is the correct url format?</p>

You can use a URL of the format:
http://maps.google.com/maps?q=Your+Location+name@latitude,longitude
http://maps.google.com/maps?q=This+is+near+Lake+Shore+Drive@41.9288,-87.6315