Think about handling a phone call on your iPhone. Imagine the process of changing audio sources (switch from your car or AirPods to the speaker or handset, for example). Imagine switching to some other app to look something up while you are on the call, with that call status bar taking up the top of the screen.
Now take a look at this tweet, watch the embedded video:
CallBar XS – new concept UI implemented… coming soon! pic.twitter.com/wWk6g3iDwM— Elias Limneos (@limneos) March 4, 2019
I love this concept. I believe it is a jailbreak app, not something a third party could ship on mainstream iOS. But there’s a tremendous amount of flexibility being shown here.