How to design the UI for two data point inputs for routing

I have a large list of items (about 500) on my iphone app.. I am creating a custom map which uses the user's input of a "to" and "from" locations (places).. I am brainstorming the best way to collect the input from the user. Ideally, a search bar with a table view that has the matching items (instant search).. I could ask the user to enter the "To" location and "From" destination and then present the custom map with the route.. I am trying to figure out the ideal way to do this such that it remains simple and user friendly.. I could have;

1) A search bar/table view that asks for the From location which, once entered, goes to a similar second view that takes the To location (could be too annoying for the user)

2) Each input area takes half a view (From is top, to is bottom).. however too cluttered

3) One view with the items, the user selects two locations from the list (in this case, it is not very intuitive.. how would I let the user know that he is supposed to select two items.. what if he messes up the order or forgets he clicked on an item as he searches?)

Note that I am not asking for the code, just an idea on how to design this UI to be simplistic and easy to use

Thanks!

You could have two search bars with a drop down list that provides the instant search (kinda like google's instant search) once the user enters the first selection it freezes and goes to the "TO" bar...