Preview at WWDC likely in June, followed by September launch.
Apple Seeds Third Beta of iOS 9.3.2 to Developers
iOS 9.3.2 beta 3 can be downloaded over-the-air using the beta configuration profile or through the Apple Developer Center.
iOS 9.3.2 is the second minor update to iOS 9.3, coming after iOS 9.3.1, an update that introduced critical bug fixes. iOS 9.3.2 appears to fix a major Game Center bug that has plagued some iOS users for months and it reintroduces the ability to use Night Shift and Low Power Mode simultaneously.
Aside from those tweaks, there appear to be no outward-facing changes, with the update focusing on under-the-hood improvements. Any new features or fixes found in the third beta will be listed below.