The CTTypesetter opaque type represents a typesetter, which performs line layout.


Line layout includes word wrapping, hyphenation, and line breaking in either vertical or horizontal rectangles. A typesetter object takes as input an attributed string and produces a line of typeset glyphs (composed into glyph runs) in a CTLine object. The typesetter performs character-to-glyph encoding, glyph ordering, and positional operations, such as kerning, tracking, and baseline adjustments. If multiline layout is needed, it is performed by a framesetter object, which calls into the typesetter to generate the typeset lines to fill the frame.

A framesetter encapsulates a typesetter and provides a reference to it as a convenience, but a caller may also choose to create a freestanding typesetter.