Friday, February 22, 2008

How to Create a "LoJack" Program for Your iPhone

Set Up a Private Twitter Account To Phone Home


[Via The Unofficial Apple Weblog]
Way back, one of The Unofficial Apple Weblog readers begged for an iPhone LoJack solution. He wanted his iPhone to "call home" regularly in case of loss or, let's be more realistic, theft. Over the past week, I finally had a chance to give this request some time, and I put together findme. It's a command-line program that returns the location of the cell phone tower nearest to your iPhone. When run, it tells you the tower id, plus its latitude and longitude courtesy of Google Maps.

To do this, create a new Twitter account just for your iPhone (it will need its own unique email address, separate from your main account, so have one handy). Open the Settings panel, and look for the "Protect My Updates" checkbox. It's towards the bottom of the page, just above the Save button. Check this and click Save. With protected updates, only the Twitter users you approve will see the updates for this iPhone-only account (just you? you + spouse? spouse, kids, and "special friends?" Up to you).

After creating your phone's Twitter account, you're ready to set up your iPhone to tweet in on a regular basis. Here's how.

1. Install findme Add findme to your local binaries folder. Under 1.1.3, I've been using /var/root/bin for my utilities. If you use another location, substitute that path for mine. Make sure to chmod 755 findme so that it can be executed.

2. Make sure you have curl It's a standard part of the BSD distribution, if memory serves. You'll need it to contact Twitter. Your iPhone will only be able to call in via curl and Twitter if it has Internet access, through EDGE or WiFi.

3. Create a tweet shell script Copy the following text into a new text file, and add it to your binaries folder.

#! /bin/sh
curl --basic --user username:password \
--data status="`/var/root/bin/findme`" \
Use the proper path to findme and substitute your actual username and password. Make the file executable, i.e.

chmod 755 tweet
4. Create a launch daemon In /System/Library/LaunchDaemons, you'll find a simple daemon that runs once a day, called Copy this to com.sadun.tweet.plist, and edit it as follows:

Update the Label to com.sadun.tweet.
Kill the two lines that relate to "nice". You don't want your lojack to be usurped by other processes.
Change the program arguments to /var/root/bin/tweet.
Change the start interval from 86400, according to your needs. 86400 is once a day (60 seconds * 60 minute * 24 hours). Right now, I have mine running every ten minutes (600) because I needed to check that the LaunchDaemon was functioning properly.




5. Reboot. This allows our iPhone to restart, loading your new launch daemon.

No comments: