Just come across this problem in one of my apps that has the bottom tab bar as an important part of the app design, the change destroys the look and feel of the app completely and will require months of redesign to try integrate this new format. In the mean time this will make the current app unusable if the user upgrades the OS, and seems to crash the app in some situations that use a custom tab bar. Very annoying and poorly thought out change to the OS without giving us developers any time to come up with reasonable solutions.. what the hell are they thinking?

I don't like the new TabBar it is a confusing view and not very well implemented. It also means there are two ways the Tab Bar will appear depending on the OS version. This makes it very difficult to design an App that will look consistent across older iPads. It also breaks the older programs if they run on 18 where the code for hiding TabBar has been used as doesn't seem to work on 18. Please allow the developer to choose the previous implementation to ease the transition to the new ways