Robert Price

Previously I’ve covered how to link into the iTunes COM library from VB 2005 to show now playing information. This article assumes you have already read that, or have it to hand.

Taking this application further, wouldn’t it be useful for our application to automatically update itself when a track changes takes place on iTunes?

Well I hope you are saying yes, as it’s what I’m going to cover now.

iTunes can inform our application of changes of track if we choose to listen for it’s OnPlayerPlayEvent event.

If you are not sure what an event is, it’s basically a way for one program to tell another that something has happened in that program and the other program may wish to react to it. In this case, a different track has started playing in iTunes.

So how can we get our application to listen out for this? Well firstly we need to say that our programme is interested in these events. We do this by using VB 2005’s WithEvents keyword when we create our interface into iTunes.

So previously we did this using the following code.

Now we have to add in the WithEvents keyword as follows.

Now our program can listen out for events from iTunes. You may have noticed I’ve changed Dim to Private. This is because for this example I’m going to use a Windows Application and not a Console application as before.

Next we have to create our event handler so we can react to the events iTunes is sending us.

The easiest way to do this is use the method generator at the top of the code view in Visual Basic 2005 Express Edition. My iTunes object is called app so we select this, then OnPlayerPlayEvent to create our event handler stub.

This passes in the variable iTrack as an Object. We know this is really an IITTrack object, so we need to cast it as such.

This creates a new varible called track and casts the existing iTrack variable as an IITTrack using CType.
Doing this, we have easy access to the track data passed to us by iTunes in the event.
We need to do something with this information seeing as we’ve gone to all the trouble of asking iTunes for it. The easiest thing to do is to just display a small window with the name of the current track.

Obviously this is a simplified version of a real program, but it should give you an idea of how to get events from a remote program into your VB2005 application.

As I’ve been using VB 2005 a lot more a work the past few weeks, I thought I’d rewrite my iTunes Now Playing console app in VB.

It does the same as the previous C# example, and again I’ve chosen to use the free version of the language and Microsoft’s Visual Basic 2005 Express Edition.

The first thing to do, is to make sure you have downloaded the iTunes SDK from Apple.

In Visual Basic, create a new Console Application. We need to add a reference to the iTunes COM library, so we do this by right clicking over our application in the Solution Explorer, and selecting “Add Reference…”. Select the COM tab, and scroll down to find the iTunes library. Mine was called “iTunes 1.7 Type Library”.

Now for some code.

Firstly, like all good programmers we turn on VB’s strict mode to make sure we’re not using too many bad programming practices.

Next we need to import the libraries we want to use. In this case, System> and iTunesLib.

As we’ve created a Console App in VB, we can just drop the following code into the Main sub.

Firstly we need to create an iTunesApp object so we can get talk to iTunes. After that we need to get the current track.

We should now have the details of the current track in the track object so we just need to print these to the console.

Finally, just so we can see the result we need to wait for the user to press return before we exit.

Fire up iTunes if it’s not already on and start a track playing. Now start your VB program, and it should tell you the current track title and artist as shown below.

It’s as simple as that. Obviously I’m not checking for exceptions and errors as this is just an basic example.

Your final code should look something like this.

I’ve been playing about with the COM interface to Apple’s iTunes running on a windows machine with .NET installed.

My choice of language has been C# as it’s a bit more Perl like than VB. I’ve used Microsoft’s “free” Visual C# Express in this case.

The iTunes SDK is available from Apple and has all the documentation needed.

I’m going to run through how to get Now Playing information out of iTunes. The quickest way to do this is as a console application.

Start up Visual C# and create a new console application. I called mine NowPlaying.

You’ll need to add a reference to the iTunes come library. Do this on the righthand side of the C# project window by right clicking and selecting “Add Reference…”, selecting the COM tab, and finding the iTunes library.

The first thing you’ll need to in your code is to import the iTunes namespace to make the code look a little cleaner. We’ll also need the System interface for our console input and output.

In your Main method, the first thing we need to do is to create an instance of the iTunesAppClass. I’ve rather originally called mine, app.

Next we need to get the current track. This is a simple attribute call to the app object.

Finally we need to show the current track. To do this we call two attributes on our track variable, name and artist. There are plenty of other attributes we could call, but these are the two most useful for this example. See the SDK for more choice.

Once we have displayed our name and artist, we need to wait for the user to hit return. This is useful if our program wasn’t launched from a console window as it would end before we’ve had a chance to read any output.

That’s it, nice and easy.

Here’s the full .cs source code.