NSSpring protocol declares methods that the destination object (or recipient) of a dragged object can implement to support spring-loading—the act of dragging an object onto a destination object and hovering or force clicking to activate the destination object.
- macOS 10.11+
A view can be configured as a drag-and-drop destination, a spring-loading destination, or both. If a view implements both drag-and-drop and spring-loading, then it will receive messages for both operations.
Note that the view beneath the cursor during a drag receives priority. For example, if a parent view implements drag-and-drop and a subview implements spring-loading, then the parent view will not receive drag-and-drop messages while the cursor is over the subview.