Could the iPhone soon be able to track your location in the background as you walk around? A hint that such a capability is in the works at Apple comes from a programmer friend who spent some time spelunking around inside iPhoto '09, which shows traces of being able to associate such GPS log data with photos.

That could provide geotagging information for photos taken with another camera, or it might let you view a map of your travels, with pins dropped where you'd taken photos with the iPhone.

My source points to an unused nib file within iPhoto as evidence of this feature. As you can see from the screenshot and the text below, it's assuming that there's a Location app on the iPhone, and that app must be running to transfer location data to iPhoto.

[image link] [1]

Activate the location application on your iPhone or iPod Touch. Once selected, any available location information will be transferred to your iPhoto library and associated with the photos in the selected event(s).

Elsewhere, in the iPhoto binary, there's also this string, which appears to provide the iPhoto side of the directions:

Select an iPhone or iPod Touch from your list of named devices. Once selected, the appropriate information will be transferred to your iPhoto library and associated with the photos in the selected event(s).

The user experience seems rather convoluted, since the implication from these strings is that you would have to select one or more events in iPhoto, then launch the app on the iPhone to transfer location information via Wi-Fi. Quibbling with the interface is pointless, though, given that this feature is non-functional in iPhoto '09, and there's no known Location app in the iPhone with which to connect.

Setting the speculation phasers on stun, therefore, ponder the following:

• One of the issues with the iPhone is that independent apps can't stay active in the background, so GPS-based apps must be onscreen at all times to capture location data. Apple isn't subject to that limitation, so a Location app from Apple could track location no matter what you're doing. Apple should open that capability up to developers as well.
• The text mentions the iPod touch, which is a bit odd. Although the iPod touch can figure out its location from nearby Wi-Fi networks, the feature is worthless if you're anywhere but a heavily built-up urban area. And of course, the iPod touch currently has no GPS or camera. Could that be changing in a future model?
• One problem with using the iPhone's GPS constantly is that it drains the battery in just a couple of hours. I can't really see this feature being useful unless the iPhone were to get better battery life while using GPS. Or, I suppose, the Location app could rely largely on cell phone tower triangulation (which I suspect works better inside buildings anyway), using GPS occasionally to improve accuracy when available.
• The text talks about the location data being associated with "the photos in the selected event(s)." That could be interpreted to mean that the Location app's data could be used to geotag photos from non-GPS-capable cameras, much as you can do now with a GPS data logger device and a program like HoudahGeo [2] or Ovolab's Geophoto [3]. Since so few cameras offer GPS support right now, those programs remain extremely useful for automatic addition of location information.
• iPhoto '09 can already show you a map containing your geotagged photos from the iPhone, and it can show a path between photos within a map in a book, but it's just drawing lines between photo locations - it doesn't actually know the path you took between the points where you took the photos. This feature could enhance such maps with your actual path.

In the end, there's no guarantee that Apple has done more than toyed with the idea of garnering additional location-based data for iPhoto's geotagging feature. Such a feature would need to be designed and introduced extremely carefully, to ensure that users had sufficient control over it to avoid privacy concerns, and to ensure that the messaging around the app didn't give the wrong impression. Given that many of the marketing blurbs for the GPS data logging devices gleefully suggest privacy-infringing uses like spying on a teenager, spouse, or employee, caution on Apple's part seems entirely warranted.

[1]: http://www.tidbits.com/resources/2009-02/PhoneLocationBrowser-nib.png
[2]: http://www.houdah.com/houdahGeo/
[3]: http://www.ovolab.com/geophoto/

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