tracking
The amount to modify the default tracking.
Declaration
static let tracking: NSAttributedString.KeyDiscussion
The value of this attribute is an NSNumber object containing a floating-point value. The value represents the amount of space, in points, to add between the specified characters. A positive value increases the spacing between characters, and a negative value brings the characters closer together. Specify 0 to disable tracking.
The effect of this attribute is similar to the effect of kern, but the system treats tracking as trailing whitespace. A nonzero amount of tracking disables nonessential ligatures, unless the ligature attribute is present.