I stumbled upon an interesting behaviour after upgrading to iOS 10. It seems that when password is too long - the app freezes when font of the text field is bigger than "min font size" and "adjust to fit" is checked. The app freezes when I try to input more characters than fit into input width. iOS <10 don't have this problem.
Text field settings: in red - the changes from default values, in orange - difference between two text fields that prevents freezing.
I am not sure why this is happening, and while I managed to solve it by unchecking the "adjust to fit" I would appreciate if anyone can explain why is this happening. Maybe it is a requirements that font should be <= "min font size"? I haven't found any info on that.
Sample repo: https://github.com/sQu1rr/test-ios-freezing-password