How to install previous iOS versions in XCode (only iOS 4.3 is visible)

I've recently bought a new computer, installed XCode 4 on it (which comes with the iOS version 4.3 of the SDK) and moved over all of my old projects from my previous computer (which was also running XCode4 as well but iOS version 4.0).

Im facing two major problems now:

1) All of my projects compile fine, but crash upon loading in the simulator (I get a hex dump and the message "Program ended with exit code: 1"). All of this is still working fine on my previous computer and I cant seem to figure why this would be happening here. The only solution I came to was on a forum which suggested there was a bug with apple that wont allow the new sandy bridge mac's to build anything targeted at iOS 4.3 in the simulator. Is this correct? Are there any other possible reasons why they are crashing on a fresh install all of a sudden?

Which brings me to my second question:

2) When I try to build my XCode project - the only options that are available to me are related to iOS 4.3 (i.e. iPhone or iPad - I have attached a screenshot)

- What I would like to do is target the base iOS 4.0 and see if I can build for that, but for the life of me I can't seem to find a way to install / include the previous iOS versions and make them available in XCode. How can I do this? Any suggestions?

Thank you to the community in advanc开发者_JAVA百科e!

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1) I can't figure it out. Sorry.

2) It seems that there is no easy way to use old iOS versions in Xcode 4.1

If your Xcode is 4.0 try to change here.