Apple has released a new beta of iOS 8.3 to developers and AppleSeed testers. It is available for download over the air, or through the Apple Developer Center.
This is the fourth beta of iOS 8.3 for developers, and the second AppleSeed testers. Apple started the invitation-only Apple Seed beta for iOS 8.3 just under two weeks ago.
Developers can also download the latest beta of Xcode 6.3, build 6D554n, which contains a pre-release version of the next update to Apple's Swift programming language, version 1.2. This build also contains the SDK for iOS 8.3 beta 4.
Source: Apple Developer Center