Comments on: An Overview of the iPhone Architecture

By: Vagrant

Vagrant — Fri, 07 Aug 2009 00:29:03 +0000

Ah, I understand now. When you said, “but up until the 3.0 beta” I thought you meant that the 3.0 beta finally allowed it, but I misunderstood.

Thank you for your very educational article and feedback. It’s quite refreshing!

By: Anthony

Anthony — Thu, 06 Aug 2009 12:28:46 +0000

@Vagrant

It is _possible_ via jailbreaking, which I’m pretty sure I either referenced or hinted at in the article.

http://thecoffeedesk.com/news/index.php/2009/07/20/iphone-firmware-definition/ – as Mark said in another article, iPhone OS is just Darwin Unix, allowing daemons to run in the background etc.

I wouldn’t recommend this, but you could conceivably write an app that inspects the value of a text file on a webserver. Once the app passes Apple review, you could change the value of the text and have the app download some precompiled ARM code to run as a daemon in the background.

I might write this in an article (think I will), but its just one way to achieve daemon programming until Apple allows it “officially”.

But, all the more reason, jailbreaking prevails as the way to do what you really want to do with the iPhone.

By: Vagrant

Vagrant — Thu, 06 Aug 2009 04:42:24 +0000

Anthony, you indicated that in OS 3.0 the iPhone could run non-Apple apps in the background, but I have not found a way to do this. In fact, most reports say it is still not possible. I am trying to write an alarm app that sends an alert to the user at random times during the day. Obviously not a battery hog, but seemingly not possible.

By: nilges

nilges — Sun, 07 Jun 2009 15:33:27 +0000

Getting it to stream to a real AirTunes server (i.e. an Airport Express) is all I really had in mind. Just one of those things that one assumes should be possible right out of the box, but isn’t. The program that makes this possible on Macs for sources other than iTunes is called Airfoil, by Rogue Amoeba, who has the most extensive discussion of doing this for iPhone in a blog entry here:
http://www.rogueamoeba.com/utm/2008/12/12/thoughts-on-airfoil-for-iphone/

By: Anthony

Anthony — Sun, 31 May 2009 20:47:03 +0000

I haven’t read the O’Reilly book on iPhone development, but as far as having “Open” iPhone development, it really depends on how “open” you’re trying to be without jailbreaking. A pulseaudio-like application for the iPhone would be difficult without direct hardware access for the reasons you suggested: DRM, and Apple hardware trade secrecy.

You might have better luck convincing an iPhone to stream to a computer/device “pretending” to be AirTunes, although some handshaking research is needed. After capturing the stream, you could then manipulate it like you’d want or route it to another device (such as a pulseaudio node). I hope that helps, because there’s not much to be done to circumvent Apple’s hefty restrictions on iPhone development.

By: nilges

nilges — Thu, 28 May 2009 17:17:09 +0000

I knew it was unsupported now, and probably will be forever, since access to raw audio data circumvents DRM. Only thing I’ve heard about in 3.0 that remotely applies to this is allowing apps to access the iTunes library, but almost certainly just for API-managed playback. Macs even need a third-party app to output anything besides iTunes to Apple’s AirTunes. The jailbreakers have done some amazing things. Can you suggest any resources for what’s currently known about iPhone Open Application Development? There’s an O’Reilly book by that title written by someone in that community. Any good?

By: Anthony

Anthony — Sun, 24 May 2009 00:41:25 +0000

@nilges: This is currently (as far as I know) not supported by the iPhone’s APIs and frameworks, but jailbreaking offers the functionality you are suggesting via currently experimental kernel modification via hotpatching and/or loadable drivers. You can probably experiment with this until Apple releases a sort of global sound redirection feature to its API, to get pulseaudio-style remote streaming.

By: nilges

nilges — Sat, 23 May 2009 19:35:58 +0000

Great article. So given how much Apple would like the iPhone to remain a closed system, what do you think would be the best approach to coding something (app? device driver?) that could intercept any audio being played by other apps and DO THINGS with it, like, oh, say, stream it to a music server over WiFi?