kCMTextMarkupAttribute_OrthogonalLinePositionPercentageRelativeToWritingDirection
The placement of the first line in a block of text as a percentage in the direction orthogonal to the writing direction.
Declaration
let kCMTextMarkupAttribute_OrthogonalLinePositionPercentageRelativeToWritingDirection: CFStringDiscussion
This attribute’s value must be a non-negative CFNumber that expresses the position of the center of the cue relative to the writing direction. The line position is orthogonal (or perpendicular) to the writing direction — that is, for a horizontal writing direction it’s vertical, and for a vertical writing direction, it’s horizontal. This attribute expresses the line position as a percentage of the dimensions of the video frame in the relevant direction. For example, 0 percent is the top of the video frame and 100 percent is the bottom of the video frame for horizontal writing layout.
If you use this attribute, apply it to the entire attributed string.