A common pattern in desktop Cocoa apps is to have a parent NSView manage a collection of NSView siblings. An example would be an NSView acting as a drawing canvas containing a collection of NSViews that represent lines and shapes. LJSelectionView manages those sibling views and their selection.
As of 10.5 the drawing order of sibling views is guaranteed and can be set by the addSubview:positioned:relativeTo: method in NSView. What we're still lacking is the ability to draw an overlay over a set of NSViews (say to draw a selection rectangle) or to directly draw in front of a NSView's subviews.
To overcome these limitations, LJSelectionView and its supporting classes manage the subview hierarchy to allow us to draw a custom selection rectangle and custom highlights (to show what subviews have been selected). This is done transparently and the drawing styles of either can be easily customized by subclassing (or modifying) LJSelectionItemView and LJSelectionRectView.
All included classes are configurable for common options and are easy to subclass or modify if they don't do exactly what you're looking for.
Copy the four files: LJSelectionViewController.m, LJSelectionView.m, LJSelectionItemView.m and LJSelectionRectView.m and their headers to your project. Recreate the view hierarchy and make sure all outlets are hooked up in IB (you can check the demo to see how it's setup). It is possible to setup the view hierarchy without IB you just have to make sure the right connections are made.
An MIT license is included in the root directory of this repo.
LJSelectionView supports both ARC and non-ARC projects without modification.
The included application tests are not automated in any way. To run the tests, open the project in Xcode and press ⌘-U.
If you fork/copy this repo I recommend you link the pre-commit file in .hooks to your local .git/hooks directory. It copies the main source files and their headers from the demo project to the root directory. I didn't think a submodule was worthwhile in this case.