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# Protocol Implementations

Access the split view controller’s implementations of protocol methods.

## Discussion

[`NSSplitViewController`](/documentation/AppKit/NSSplitViewController) conforms to [`NSSplitViewDelegate`](/documentation/AppKit/NSSplitViewDelegate) to serve as its split view’s delegate. This page lists the split view controller type’s implementations of those protocol methods. If you override these methods in a subclass, you must call `super`.

[`NSSplitViewController`](/documentation/AppKit/NSSplitViewController) also conforms to [`NSUserInterfaceValidations`](/documentation/AppKit/NSUserInterfaceValidations) by implementing [`validateUserInterfaceItem(_:)`](/documentation/AppKit/NSSplitViewController/validateUserInterfaceItem(_:)).

## Topics

### Configuring and Drawing View Dividers

[`func splitView(NSSplitView, effectiveRect: NSRect, forDrawnRect: NSRect, ofDividerAt: Int) -> NSRect`](/documentation/AppKit/NSSplitViewController/splitView(_:effectiveRect:forDrawnRect:ofDividerAt:))

Allows the split view controller to modify the rectangle where mouse clicks initiate divider dragging.

[`func splitView(NSSplitView, shouldHideDividerAt: Int) -> Bool`](/documentation/AppKit/NSSplitViewController/splitView(_:shouldHideDividerAt:))

Allows the split view controller to determine whether the user can drag a divider or adjust it off the edge of the split view.

[`func splitView(NSSplitView, additionalEffectiveRectOfDividerAt: Int) -> NSRect`](/documentation/AppKit/NSSplitViewController/splitView(_:additionalEffectiveRectOfDividerAt:))

Allows the split view controller to return an additional rectangle where mouse clicks can initiate divider dragging.

### Managing Subviews

[`func splitView(NSSplitView, canCollapseSubview: NSView) -> Bool`](/documentation/AppKit/NSSplitViewController/splitView(_:canCollapseSubview:))

Allows the split view controller to determine whether the user can collapse and expand the specified subview.

[`func splitView(NSSplitView, shouldCollapseSubview: NSView, forDoubleClickOnDividerAt: Int) -> Bool`](/documentation/AppKit/NSSplitViewController/splitView(_:shouldCollapseSubview:forDoubleClickOnDividerAt:))

Allows the split view controller to determine if a subview collapses in response to a double click.

### Validating User Interface Items

[`func validateUserInterfaceItem(any NSValidatedUserInterfaceItem) -> Bool`](/documentation/AppKit/NSSplitViewController/validateUserInterfaceItem(_:))

Returns a Boolean value that indicates whether to enable the specified item.


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