# init(x:yStart:yEnd:) Creates a vertical rule mark with an x encoding and y interval encoding. ``` nonisolated init(x: PlottableValue, yStart: PlottableValue, yEnd: PlottableValue) where X : Plottable, Y : Plottable ``` ## Parameters `x` The value plotted with x. `yStart` The value plotted with y start. `yEnd` The value plotted with y end. ## Discussion ### Discussion Use this initializer to create a vertical line at y positions from `yStart` to `yEnd` to an x position: ```swift Chart(data) { RuleMark( x: .value("Pollen Source", $0.source), yStart: .value("Start Date", $0.startDate), yEnd: .value("End Date", $0.endDate) ) } ``` ![Vertical rule chart with y-axis showing the month in the year 2020 starting with January and ending with December, and with x-axis showing a pollen source: Trees, Grass, and Weeds. There are 4 rules. 2 for Trees 1 starting in January and going until the end of September and 1 spanning December, 1 for Grass starting in March and going until the end of August, and 1 for Weeds starting in April and going until the end of November.](images/com.apple.Charts/LineSegmentMarkSwift.LineSegmentMarkVerticalLineSegmentChart@2x.png) See [`RuleMark`](/documentation/Charts/RuleMark) for the setup of the structure that contains the `startDate`, `endDate`, and `source` properties. --- 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)