OT: Starting IOS development, can't upgrade Xcode/IOS

[Graham Samuel]

Sorry for the interruption, but many months after signing up for IOS development I have time to start building my first IOS app with LiveCode. I have the necessary licences from Apple and RunRev, and I already have a version of XCode and all developer tools on my Mac, which is running the latest version of Lion. 

However, I know via emails from Apple emails that I don't have the latest version of XCode itself. This is where the problem comes in: I can't upgrade from the XCode I have now (4.1) to the most recent one (4.3) with an up-to-date IOS kit, because when I follow the Apple download links, they lead me to the App Store which then tells me I can't download because I already have XCode! It suggests I upgrade via Software Update, but that tells me that all my Mac apps are up to date. SU acknowledges the existence of XCode (in two parts) installed in October and something called XCode Install Assistant which I can't find, but doesn't give a version number. 

Finally I found an app called "Install XCode" and ran it - it said it was "updating files", but after it had finished working (it took a long time and in fact I did it twice), I still don't have any IOS 5 files and the version of XCode in my Developer directory is still 4.1.

After all that 'updating', I get this report from System Information:

Developer Information:

  Version:	4.1 (4B110)
  Location:	/Developer
  Applications:
  Xcode:	4.1 (516)
  Instruments:	4.1 (4138)
  Dashcode:	3.0.2 (336)
  SDKs:
  Mac OS X:
  10.6:	(10J567)
  10.7:	(11A511a)
  iPhone OS:
  4.3:	(8H7)
  iPhone Simulator:
  4.3:	(8H7)

I definitely do not have anything to do with IOS 5 in my Developer directory, so I'm stuck - LiveCode wants me to tell it where the developer root for IOS 5 is on my Mac, but it isn't anywhere!

I really have no idea what's going wrong. Maybe I should uninstall all my Developer directory and start again, but that seems crazy. Please can someone help me? I just can't get started.

TIA

Graham