How to test an app with an older iOS version in Xcode 3.2.6?

Xcode 3.2.6 comes with iOS SDK 4.3. Because of space I had to delete my older Xcode versions, and now I'm stuck with this: How can I run my app on the iOS 4.0 or even 开发者_高级运维3.2 simulator?

Must I download and install the older iOS SDKs? How can I install them for Xcode 3.2.6 so that they appear as an option for launching?

iOS versions are bundled within the SDK, so yes, you have to install previous versions.

Some "hacks" allows to use previous SDKs accross Xcode versions, but since it changes with Xcode versions, I abandonned that idea to do so...

I strongly suggest/recommend to keep an old device (iPhone 2G, iPod Touch) with a previous iOS version to do some on device testing, that's what I do... and have sometimes surprises with armv6 or slower CPU...

EDIT :

With Xcode 4.0.2 you can run starting at iOS3.2 on iPad, which differs from iOS3.0 and is close to 4.0. From /Developer/Platforms/iPhone(OS|Simulator).platform/Developer/SDKs :

iPhoneSimulator platform:
1003,4 MB iPhoneSimulator4.3.sdk
977,2 MB iPhoneSimulator4.2.sdk
820,6 MB iPhoneSimulator4.1.sdk
749,7 MB iPhoneSimulator4.0.sdk
693,1 MB iPhoneSimulator3.2.sdk

iPhoneOS platform:
358,8 MB iPhoneOS4.3.sdk