i recently installed iphone sdk 4.0 on the laptop mac 10.6.4 snow lopeared
my iphone device OS firmware is 3.1.2 so can this new SDK 4.0 work on my iphone or i have to update my ipohone to work on OS 4 i mean is there somewhere in the new xcode to set the iphone to 3.1.2 ??
Many thanks for all
In target settings there is "iPhone OS Deployment Target" setting - set it to appropriate OS version so your program will be compatible with it.
Remember also that if you make some calls from new APIs (e.g. appeared in 4.0) you must check if they are available in run-time to avoid application crashes when run on older OS versions.