iOS4: Correct SDK and Deployment Target Settings in Xcode

I upgraded my Xcode from 3.1.2 to Xcode Version 3.2.3 and upgraded my device to 4.0 OS. I have set my Base SDK to iPhone Device OS 4.0 and the iPhone OS deployment Target to iPhone OS 3.1.2.

When I run my application (which was created in 3.1.2) on device under iOS4.0, and I see problems such as dates 开发者_运维百科not displayed and the "back" buttons not appearing in the navigation bar. The app works fine when under 3.1.2 and 3.2.

What could be causing the problems under iOS4.0? Are my SDL and Deployment settings correct?

Edit:

I have solved date issue and back button issues.

Thanks.

Your deployment settings look correct.

Do you use any third-party library in your application ? What kind of "back" buttons do you use, are they customized ?

You're settings are probably correct. The NSDateFormatter class has gotten less lenient in iOS4 and -[NSDateFormatter dateFromString:] will return nil in more cases if it runs into a problem.

There might be some quirks with xCode itself... try clean'ing all targets selecting all checkboxes, restarting and rebuilding again... as Luzal said try to update third-party libraries if you use them... Need more info, anyway...