Iphone sdk 4.0 version doubts

Question

I developed ipod sdk application in iphone sdk version 3.1.2.Its work well in ipod.Now i build the app and installed application via itunes in iphone4 , its not work well.It make crashes a lots of time.

I upgraded the sdk version to 4.0. But when i open my application it says base sdk is missing.

Can any one help me ? Thanks in advance...

Can i revert my iphone os 4.0 to 3.1.2...?

Answer 1

It's seems the previous SDK versions have been removed by Apple. Since you have a paid developer account, you should be able to download the previous SDK Versions separate from Apple's Developer site.

regards