Open Radar

 
Summary:
When setting a font on a UILabel/UITextField, it does not update if you change from a standard font to a font scaled with UIFontMetrics when the font is otherwise identical, when the preferredContentSizeCategory is large (the default).

Steps to Reproduce:
- Create a UILabel, UITextField, or UITextView
- Set a standard font (eg UIFont.systemFont(ofSize: 12.0))
- Set adjustsFontForContentSizeCategory = true
- Set an adjusted font of the otherwise same type constructed with UIFontMetrics:
    (i.e. UIFontMetrics(forTextStyle: .body).scaledFont(for: .systemFont(ofSize: 12.0)))
- Run the app on device or simulator in the default content size category.
- Live adjust the content size category with control centre or Accessibility Inspector.

Expected Results:
The font should live adjust as it has been changed to a scaled font.

Actual Results:
It does not live adapt. If you start in a non-standard content size category, the bug is not present.

This appears to be because the font returns that it is equal to the scaled font with `isEqual:`, despite the fact one is scalable and one is not, and therefore the font doesn't change.

Version/Build:
iOS 11.2.1 (15C153)