When worlds collide...
I was presented with a problem: Product Management wanted to add more attachment types. It's just a few more buttons, simple right?
At this same time, for an earlier release than attachments, I also discovered another designer on the team was working on a message priority feature, which would need a button, in that same spot. There was also a third-party integration, that only select users would see, that also needed a button -- in that same spot.
In addition, there was existing functionality, in the header, that often confused end-users, and had come up as an issue in multiple usability tests. Might as well address it all at once...
The current interface:
A quick journey through the design process
The final design
The final design incorporated all the elements required, without sacrificing any (or much) space on the input bar, and also increased the usability of several features, while allowing for adding more attachment types in the future, without changing the design. The attachments would add to the action sheet, instead of creating a new icon for each type. The message priority UI solution also satisfied user feedback on making it very clear what was being marked urgent as well as making it very obvious that something is going to be urgent, to reduce accidently sending high priority messages.