# init(xStart:xEnd:yStart:yEnd:) Creates a bar mark with fixed x interval that plots values with its y interval. ``` nonisolated init(xStart: CGFloat? = nil, xEnd: CGFloat? = nil, yStart: PlottableValue, yEnd: PlottableValue) where Y : Plottable ``` ## Parameters `xStart` The x start position. If `xStart` is `nil` then the rectangle will start at the leading edge of the plotting area. `xEnd` The x end position. If `xStart` is `nil` then the rectangle will end at the trailing edge of the plotting area. `yStart` The value plotted to y start. `yEnd` The value plotted to y end. ## Discussion ### Discussion Use this initializer to show vertical intervals for one category: ```swift Chart(data) { BarMark( yStart: .value("Start Time", $0.start), yEnd: .value("End Time", $0.end) ) } ```  --- 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)