NSView: drag subview from superview to another NSView

Question

I have an app that lays out pages for a magazine. The app lays out pages (NSViews of a class called Page) of a magazine on a NSView called MasterPage (which itself is the contentView of an NSScrollView). Think of a grid of pages in a scroll view.

The "pages" then have subviews auto placed on them that represent ads (class = Ad). I want to be able to drag these ads within their superview (an NSView of the Page class) and between subviews of MasterPage (the other Page class views).

I can drag the Ad class NSView on the Page class NSView it was originally placed on by invoking the mouseDragged method but how can I "release" the Ad class subview from the superview and drag it to another NSView?

Hopefully that made sense.

Answer 1

When you begin a drag event, remove the dragging view from its superview, and add it to the contentView of the NSWindow. You can then drag it around the entire window. When the drag event completes, use hitTest: to determine what view you're on top of (you may have to walk back up the superview hierarchy to find the view you really want). Then add the dragging view back to the final target.

Depending on how you've implemented clipping in your views, you may be able to skip the step of moving the dragging view to the contentView. If you don't clip your page views, then it's ok for the dragging view to move all over the screen.