This is a demo for adding dragging and dropping for NSImageView. The "DragDropImageView" was from Apple's example "CocoaDragAndDrop".
CocoaDragAndDrop shows how to drag image from finder to NSImageView and drag image between NSImageViews. But it don't show how to drag from NSImageView to finder and save the image.
I added some code to ""DragDropImageView" to show how to do it. And I added two properties: allowDrag and allowDrop. They can control if the NSImageView can drag or drop.