Apple Releases iOS 4.1 SDK to Developers LIKETWEETMAIL Posted September 8, 2010 at 7:53pm by iClarified · 4766 views Following the release of the iOS 4.1 firmware, Apple has seeded the iOS 4.1 SDK to developers.The build number of the SDK is 10M2309 and it is available for download from the iOS Dev Center.Get It