In iOS 9 beta 1, there is a "Use Side Switch To:" preference allowing selection of "Lock Rotation" or "Mute", similar to iPad. As a user, I expect to enjoy this feature as I don't personally have a need to quickly disable the mute feature, but often want to lock my phone in portrait mode when reading. However, I'm noticing two immediate differences that could affect app interaction design, and I wonder if only one is deliberate.
1) Rotation lock, when controlled by the side switch, behaves like previous iPhone on-screen controls in that it locks vertically. From a development perspective, that means developers should continue to implement their own controls to force landscape when necessary. YouTube provides a good example of this with their full screen control, whereas many creative apps have only a landscape mode.
2) Mute is not available in Control Center, leaving no clear ability to acheive the mute functionality the side switch has toggled since the original iPhone. iPad has had this preference available since iOS 4, originally in the multitasking bar, then moved to Control Center as a toggle among Airplane Mode, Wi-FI, etc. Using iOS 9 beta 1, even with "Ringer and Alert" volume at its lowest and lowering media volume to "Mute" with the side rocker button, keyboard sounds are still audible. At the moment I have not discovered an accessibility control.
Has anyone else experimented with this function and gotten different results?