Open Radar

 
Area:
UIKit

Summary:
Then back button becomes truncated when changing the title from a medium length title (long enough to make it say "Back" but not long enough to remove it altogether) to a long title (one that would normally remove the title leaving only the chevron).

Steps to Reproduce:
1. Create a navigation controller
2. Push a second view controller onto it so that the back button shows "Back"
3. While still on the same view controller, change the title to something long

Expected Results:
The "Back" should disappear completely

Actual Results:
"Back" becomes truncated (i.e. "Ba…")

Version:
iOS 10.1

Notes:
Use the provided sample project on a 4.7" screen (i.e. iPhone 6, 6s or 7).

Changing between short, medium and long titles have the following results:

S -> M = Switches from the title to “Back”. Good.
S -> L = Switches from the title to no title at all. Good.
M -> S = Stays as “Back”. Acceptable, maybe not ideal.
M -> L = “Back” becomes truncated. Bad.
L -> S = Stays as no title at all. Acceptable, maybe not ideal.
L -> M = Stays as no title at all. Acceptable, maybe not ideal.

Configuration:
iPhone 7

Attachments:
https://www.dropbox.com/s/ifdqzkbefdy0yv3/SampleBackButton.zip?dl=1