Set background color of NSView and NSImageView in cocoa

Their are two way to set background color of NSView/NSImageView, which i found.

First: By Subclassing of NSView/NSImageView

- (void)drawRect:(NSRect)aRect
{
    [[NSColor redColor] set];
    NSRectFill([self bounds]);
}

Second:

Don't want to make subclass, as you mentioned in your question. Then

[_backgroundView setWantsLayer:YES];
[_backgroundView.layer setBackgroundColor:[[NSColor redColor] CGColor]]];

Here _backgroundView is the IBOutlet/object of NSView/NSImageView. You just need to access layer of NSView/NSImageView for giving him backgroundcolor without subclassing them.

you cannot draw something custom without subclassing NSView however you can change background colour of layer.

[yourView setWantsLayer: YES];
[yourView.layer setBackgroundColor: [NSColor redColor].CGColor];

In Swift you can change the NSImageView background color like this:

self.myBackgroundView.wantsLayer = true
self.myBackgroundView.layer?.backgroundColor = NSColor.red.cgColor

if you want an image as background you can use the following:

self.myBackgroundView.wantsLayer = true
let image : NSImage = #imageLiteral(resourceName: "imageResourceName")
self.myBackgroundView.layer?.backgroundColor = NSColor.init(patternImage: image).cgColor

You can apply a background color to any NSView descendant via Interface Builder by implementing a category extension like this:

@implementation NSView (backgroundColor)

- (void)setBgColor:(NSColor *)color {
    //
    [self setWantsLayer:YES];
    self.layer = [CALayer layer];
    [self.layer setBackgroundColor:[color CGColor]];
}

@end

and provide a value for it in the User Defined Runtime Attributes panel in IB: