# splitView(_:constrainMinCoordinate:ofSubviewAt:) Allows the delegate to constrain the minimum coordinate limit of a divider when the user drags it. ``` @MainActor optional func splitView(_ splitView: NSSplitView, constrainMinCoordinate proposedMinimumPosition: CGFloat, ofSubviewAt dividerIndex: Int) -> CGFloat ``` ## Parameters `splitView` The split view that sends the message. `proposedMinimumPosition` The proposed minimum coordinate limit of the subview in the split view’s flipped coordinate system. `dividerIndex` Specifies the divider the user is moving, with the first divider being 0 and increasing from top to bottom (or left to right). ## Return Value The minimum coordinate limit of the divider. ## Discussion > Important: > If your split view uses Auto Layout to size its subviews, don’t implement this method. The delegate receives this message before the split view begins tracking the cursor to position a divider. You can further constrain the limits, but you can’t extend the divider limits. If the split bars are horizontal (views are one on top of the other), `proposedMin` is the top limit. If the split bars are vertical (views are side by side), `proposedMin` is the left limit. The initial value of `proposedMin` is the top (or left side) of the subview before the divider. --- 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)