Changing the background color of an NSCollectionView - cocoa

Question

Is it a chance to programatically change the background color of NSCollectionView?
I was trying subclassing.. but not working..
#interface CollectionViewBg : NSCollectionView
in .m
[self setBackgroundColors:[NSArray arrayWithObjects:[NSColor blueColor], nil]];

Answer 1

In .m, remove this line :
[self setBackgroundColors:[NSArray arrayWithObjects:[NSColor blueColor], nil]];
And use this code:
- (void)drawRect:(NSRect)dirtyRect{
[[NSColor blueColor] setFill];
NSRectFill(dirtyRect);
}
Also don't forget to change class of NSCollectionView object in IB to CollectionViewBg.
Hope this helps :)

Answer 2

Guess subclassing isn't a great idea, because most of Cocoa controls provide various techniques to avoid subclassing in order to customize appearance and behavior.
In this particular case, you can set backgroundView property to your NSCollectionView and provide a custom view that is dedicated for drawing a custom background.
If you need to change only background color, then you can consider take advantage of the fact that collection view usually resists inside scroll view. Just set backgroundColor and drawsBackground properties of NSScrollView.

Answer 3

Here's a more modern solution. First, make yourself an NSView subclass that draws the effect you want to achieve. Here's a simple one that paints a block colour:
class ColouredView: NSView {
#IBInspectable var color: NSColor = .windowBackgroundColor
override func draw(_ dirtyRect: NSRect) {
color.setFill()
dirtyRect.fill()
}
}
Now go to your nib or storyboard and drag a custom view onto the left bar. We don't want it to be part of the view hierarchy, but we do want it to be listed under the view controller containing the collection view. Just drag it in below 'First Responder'. You can then set up any important properties or relationships - in my case, the background colour.
Finally, right-click your collection view and connect its 'background view' outlet to your custom view. This lets you do all the setup in your storyboard. If you like you can make your custom view #IBDesignable but I find that usually causes more trouble than it's worth.