Install iphone sdks side by side

Question

I'm trying to get my xCode to contain all iPhone sdk from 4 to 2. But when I upload the DMG files, it seems to only allow me to have xCode with SDK versions 2 - 3.1 OR 3.2 - 4, and not all together.

How can I install the SDK in one xCode so that I can create for all OS versions?

thank

EDIT ::

Ok, so I know that I can install the base SDK in xcode, but I only have 3.2 or 4.0 , I can’t install 3.1 or an earlier version of the SDK, how can this be done?

Final Edit ::

Well, it was resolved, basically you only need to install an older version of xcode to run early simulators, otherwise the articles provided to me in my answers, as well as others, were very useful:

http://www.clarkcox.com/blog/2009/06/23/sdks-and-deployment-targets/

Install xCode 3.2.3 with iPhone SDK 4, get “Base SDK missing”, do not see other SDKs

How to make iPhone app compatible with several versions of SDK (firmware)

http://cocoawithlove.com/2010/07/tips-tricks-for-conditional-ios3-ios32.html (possibly the best)

Answer 1

Is there any specific reason for this? Are you trying to develop applications that will work in iOS 4.x and earlier versions (3.x)? You can still create applications that will run on iOS 3.1.x using iOS 4.x sdk.

: http://www.clarkcox.com/blog/2009/06/23/sdks-and-deployment-targets/

Answer 2

, , SDK ...

XCode .
/Library/Platforms/iPhoneOS.platform/Developer/SDKs/ /Library/Platforms/iPhoneSimulator.platform/Developer/SDKs/.

, XCode .
, XCode, SDK.