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Spacetime alarms (gregdetre.blogspot.com)
29 points by gregdetre on Oct 16, 2009 | hide | past | favorite | 19 comments

The android application Locale ( http://www.twofortyfouram.com/ ) certainly seems like it could do (or come close to doing) most of these things.

That shouldn't be too hard with GPS, minus the whole "no background apps" thing: Just prompt users for a location (i.e. tap on a map) when setting an alarm, with a radius perhaps. And to accommodate the "alarm" case, just add a checkbox to "only activate while OUTSIDE this range".

Not sure if anything like this already exists either. It well might.

> minus the whole "no background apps" thing

That's kind of a huge thing - it's the difference between this idea working and not working on the iPhone... and a great example of the kind of app innovation Apple could inspire by allowing background processes.

I bought an ipod touch hoping to make some productive use of it The no background processes thing makes that next to impossible. I can't risk my fancy dancy alarm clock not going of because I went and checked my email and forgot to re-open the alarm clock program. It's a huge problem with the platform in my opinion. Heck, my Dell Axim PDA from 5 years ago would happily run 6 or 8 apps at a time.

Really? The Apple Clock program's Alarms seem to work in the background for me.

you're correct. Apple does not expose this functionality to 3rd party apps.

It does, but I didn't like it as much as some of the other options in the app store.

Apple's alarm clock program works regardless of which app you currently have open.

Apple is never going to expose straightforward background processes, as it's way too late to switch to a Pre-style 'card' model that would make it natural. Fortunately there's a solution that's complimentary to the "no background processes" restriction that I'm sure some cretins at Apple have at least mocked up, if not implemented:

They just need to expose specific interfaces to launchd (Apple's clever init/rc/cron/xinet replacement), for doing particular kinds of local notifications. An app could register (with user confirmation) that it wants to have a limited helper run when an event has occurred: cron-style schedules, at-style timers, "Moved more than X meters", "Am near X:Y", etc. The registrations would be managed just like with the current push notifications.

With that, there'd be only a few other APIs needed to absolve the want for background processes. The ability to enqueue HTTP requests would make quite a number of apps friendlier to multitasking, and its already implemented privately in MobileSafari. The ability to play audio in the background would be huge, especially combined with queued HTTP requests, but I suspect that it'd be a lot harder to squeeze out of Apple.

Loopt got around this somehow:


I guess if you fellate / pay Apple enough, they let you do it.

If by 'Apple' you mean 'AT&T' and by 'let you do it' you mean 'give you a direct line from your data center to AT&T subscriber location data with which you can approximate the feature with the Push API and no actual third party code running in the background on each phone', then I concur with your assessment.

Dedicated GPS units have had this functionality almost since day 1. We call them "anchor drag alarms" in sailing, for obvious reasons. Switch it on and go to sleep without worrying :-)

If you could integrate this with calenders and to-do lists on a hand held device you'd really have something. In general the idea of an integrated, contextually-aware smartphone would be great.

Hm, active comment moderation on the blog. Anyway, someone has indeed done this for the iphone (not that I've used it or can comment as to how well it works):


It does appear to only cover one of his use-cases, sadly. But the others would be difficult without backgrounding (and the theft alarm may require far too much polling and battery drain to ever be useful.)

Its cake on my pre. Its literally just a crontab entry and curl command and the phone tweets its gps at intervals. It be easy to watch for a tweet outside a range and alert me. Seems to add no battery drain at all. I'll have to see if I can add playing a sound locally as well.


I would hate to have my gps location constantly be tweeted, personally, but that's an awesome hack.

A fourth example:

A game where you try and assassinate your friends by setting imaginary time bombs to go off at a particular location when you think your friend will be there.

Of course it could also be built on top of something like Loopt or BrightKite if you and your friends compulsively check in everywhere you go.

I've wanted behavior-aware alarms for a long time, but this is a good first approximation.

Maybe something like that could tell me when I'm close to the grocery store that I need to buy milk.

Wait a minute... Firing up the Ycomb application right now ;p

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