How to find if the mouse is over a view

The NSView isMousePoint function works for me, without having to worry about anything CG.

func isMouseInView(view: NSView) -> Bool? {
    if let window = view.window {
        return view.isMousePoint(window.mouseLocationOutsideOfEventStream, in: view.frame)
    }
    return nil
}

Some code making use of mouse:inRect: (the recommended way; that accounts for flipped coordinates)

CGPoint point = [self convertPoint:[event locationInWindow] fromView:nil];
CGRect rect = [self bounds];
if ([self mouse:point inRect:rect]) {
}

Use NSView's convertPoint:fromView: method with fromView as nil to covert a point in window coordinates to a view's coordinate system.

After converting the mouse point to the view's coordinate system, I would use NSView's mouse:inRect: method instead of NSPointInRect as the former also accounts for flipped coordinate systems.

Alternatively, you could use a Tracking Area Object.

Something like this should work for you:

NSView* myView; // The view you are converting coordinates to
NSPoint globalLocation = [ NSEvent mouseLocation ];
NSPoint windowLocation = [ [ myView window ] convertScreenToBase: globalLocation ];
NSPoint viewLocation = [ myView convertPoint: windowLocation fromView: nil ];
if( NSPointInRect( viewLocation, [ myView bounds ] ) ) {
    // Do your thing here
}

I don't personally use this many local variables but hopefully this make this example clearer.