Foursquare iPhone app upgraded to v1.9; adds fast app switching, high res graphics and map view

Version 1.9 of foursquare’s native iPhone app is now available in the app store. The upgrade adds iOS 4′s fast app switching and high res graphics optimized for the iPhone 4 retina display. It also adds new sorting and viewing options for your friends’ locations, including a map view.

Up until now, viewing your friends’ locations on a map has been the province of third party apps like FootFeed or TwentyThree — and foursquare’s third-party developed webOS app. Foursquare has finally brought the feature to the official iPhone app, showing your friends’ avatars at their last checkin location. Touching an avatar lets you view the venue page within the app, allowing you to view it on a map, see everyone checked in there or check in yourself.

In the friends’ list you can sort by the default “recent” checkins or the new “nearby” checkins, which shows you the friends nearest to your current location. This is a nice addition since it makes it easier to find the friends you’re most likely to try to meet up with.

The app also now features fast app switching on iOS 4, which allows it to be “frozen” when you switch to another app and pick up right where you left off when you return. The graphics have supposedly been upgraded to high resolution to support the iPhone 4′s retina display, but in my testing the badge and category icons retained their jagged appearance even after deleting and reinstalling the app. This is especially odd given that the icons provided through foursquare’s API were upgraded this afternoon.

The new additions — especially the map view — are welcome upgrades to the foursquare app. Get the update and let us know how you like the new features in the comments.