I know iam asking the question asked by many, but still have doubt in this concept. I have set my "Active SDK" and "Base SDK" to 4.1 and "Deployment Target tp 3.0". Will by application run in all device upto 3.0 ?
I have one more doubt, while creating the distribution provisioning profile, i should set the "Active SDK" to 4.1 right?
Your device will run on 3.0 firmware, but nothing before then. Your active SDK should always be the SDK you have installed. In this case, 4.1 for iPhone apps.
The Deployment Target sets the lowest iOS version that app under which the app will try to run, not the highest.
With your settings, an app will start to run under 3.0, and continue to run unless you use APIs that 3.0 does not support; and the app optionally can use APIs for OS versions up to 4.1; and the app should even be able run under later OS versions higher than 4.1, unless Apple changes something or removes an API deprecated in 4.1.