Just installed the latest iphone sdk 3.0. after i seleced the active sdk as simulator3.0 at the drop down overview, the "target" field no longer shows me the 2.2.1 SDK, and defaults to 3.0, resulting i cannot test on my 2.2.1 device.
What actions should I follow to fix this? even in target property my base sdk still appear device 2.2.1
Thanks in advance.
You cannot run an iPhone application compiled for 3.0 on a device running anything other than 3.0 as it is not backwards-compatible with 2.2.1. You'll need to upgrade your device in order to run 3.0 apps on it.
More specific to the most recent release of the SDK, there is an entry in the release notes that states that this version does not let you compile against any SDK except the 3.0 SDK. I believe the last version that allowed you to do that was 3.0b2. You'll need to roll back to that one or earlier if you want to compile using the 2.2.1 SDK.
The setting you may want is the "iPhone OS Deployment Target" at the bottom of the Deployment section of the Info window for your project.
You can leave the "Base SDK" setting set to 3.0, and set the "Deployment Target" to an earlier version like 2.2.1.
search for "Target an earlier iPhone OS release" in
Then it's up to you to make sure your application doesn't try to use OS 3.0 features on an OS 2.2 device. (use weak references to any OS 3.0-only frameworks, check OS version before doing things that only work on some versions, etc.)