Apple set music geek hearts on fire on Thursday, as it confirmed that it has approved Spotify's iPhone application for distribution on the App Store. But there's not a lot of detail that's been given about the application itself. Here's five things that you might not know about Spotify's iPhone app:

1. It has almost all the features of the desktop version


Spotify has very carefully built in almost every single feature of the desktop version. There's the same super-fast streaming, the same playlist syncing functionality, and the same massive catalogue of four million tracks.

But it does lack a couple of things. There's no play queue, so you can't sneak a single track of something else into whatever album or playlist you're listening to, in the same way that you can on the desktop. Nor is there any radio functionality, though given it was always a bit rubbish in the first place you might not miss it.

2. Upto 3,333 tracks can be stored for offline listening


That's right. Spotify has confirmed that the rather odd number of 3,333 songs can be stored in playlists to listen to offline. They'll take up space on your device, obviously, so go easy with that one. Assuming the files are 3MB or so each, a full library will take up 10GB!

However, once you've got them saved, you'll be able to listen to them wherever you like - on the train with no reception, or even on the tube if you're a Londoner. Songs are easily deleted from that cache if you run out of room.

3. It works fine on the iPod touch


Don't worry if you haven't sprung for the full iPhone experience, the Spotify application will also work fine on the iPod touch, as long as you're in some form of Wi-Fi reception. The same storing songs offline will work too.

4. You'll need to be a Premium subscriber to use it


The app is free to download but due to the difficulty of sending adverts to users who are listening to Spotify offline, as well as the need to make a bit more cash, the company has decreed that only Premium subscribers can listen to Spotify on their mobile phones.

A subscription will cost you £10 per month, but will also give you access to some exclusive content before regular users, remove ads from your desktop Spotify, add the ability to listen from anywhere in the world and provide higher sound quality on the desktop app - up to 320kbps. The mobile app only goes up to 160kbps, though.

5. It can't run in the background


Unfortunately, unlike the Android platform, iPhones only let you run third-party applications in the foreground, ostentiably so that they don't bog down the system if they're intensive. That means that if you get a text, or want to check something on the web, you'll have to stop the music.

But happily the applciation remembers where you are when you close the app, and will kick things off at the exact same point when you start it up again. Your epic 45-minute post-rock songs are safe.

Bonus! A couple of other little things


The Spotify application doesn't yet scrobble your tracks to Last.fm, so if you're a fan of that functionality on the desktop app, then you'll have to live without until Spotify can bring out an update.

Also, interestingly, the mobile app operates differently to the desktop version in that it doesn't use P2P functionality to ensure rapid delivery of your content. Instead, it uses "some other methods to make it super quick", the company told Pansentient League.

Conclusions


The Spotify aplication has been approved, so should be appearing in the app store within the next few days. Neither company has given any firmer timeline than "soon" but now that the hard work's been done, it shouldn't take long to roll it out across Apple's server infrastructure.

Have you got any questions about the app? We know pretty much everything there is to know about it, so if there's something you'd like to know that hasn't been covered above, then don't hesitate to ask in the comments below.