# CTLineGetTypographicBounds(_:_:_:_:) Calculates the typographic bounds of a line. ``` func CTLineGetTypographicBounds(_ line: CTLine, _ ascent: UnsafeMutablePointer?, _ descent: UnsafeMutablePointer?, _ leading: UnsafeMutablePointer?) -> Double ``` ## Parameters `line` The line whose typographic bounds are calculated. `ascent` On output, the ascent of the line. This parameter can be set to `NULL` if not needed. `descent` On output, the descent of the line. This parameter can be set to `NULL` if not needed. `leading` On output, the leading of the line. This parameter can be set to `NULL` if not needed. ## Return Value The typographic width of the line. If the line is invalid, this function returns `0`. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)