Can I deploy app to iphone 3gs iOS 4 from XCode_3.1.4_iPhone_SDK_3.1.2 directly

Currently I installed XCode_3.1.4_iPhone_SDK_3.1.2 on Mac OSX 10.5.8, and I plan to buy an iphone 3gs 8G iOS 4 in the following days. I heard from friends that iOS 4 can't be downgraded to 3.x!

My question is, can XCode_3.1.4_iPhone_SDK_3.1.2 depl开发者_运维技巧oy app to iOS 4 device via iDP? Should I upgrade system to 10.6.4 and install Xcode_3.2.3_iOS_SDK_4.0.2?

For jailbreak iOS 4, does ldid still work well? Or some other tools for code signing?

I didn't try with iOS 4 yet, so could you give me some help, thanks in advance.

Email/MSN: linkou.bian@gmail.com

Im not sure if this has been changed, but you used to be able (when xcode was around 3.1ish) still be able to install onto 2.2.1 even though xcode didnt recognize it. Just had to build the app with deploy targetted to 2.2.1 and then get the .app and move it to itunes, then sync your itunes with the phone and it worked.