> > There's AbstractFont>>widthOfString:.  Is asking a font how 
> > much space its representation of a character needs fundamentally
> > incorrect?
> 
>   The assumption behind it is that the width of a "character" stays
> same wherever it is.  Some characters in some languages change its
> "width" based on the characters around it.

Almost all languages/fonts have glyphs which should be spaced differently
based upon context. It's typically represented by kerning pairs where
character pairs get "extra spacing" values. Often, this is just a crude
workaround for ligatures (such as ff) which really should be represented by
an individual glyph but it's "better than nothing".

Cheers,
  - Andreas