How do I make an NSView move to the front of all NSViews

Here's another way to accomplish this that's a bit more clear and succinct:

[viewToBeMadeForemost removeFromSuperview];
[self addSubview:viewToBeMadeForemost positioned:NSWindowAbove relativeTo:nil];

Per the documentation for this method, when you use relativeTo:nil the view is added above (or below, with NSWindowBelow) all of its siblings.

Another way is to use NSView's sortSubviewsUsingFunction:context: method to re-order a collection of sibling views to your liking. For example, define your comparison function:

static NSComparisonResult myCustomViewAboveSiblingViewsComparator( NSView * view1, NSView * view2, void * context )
{    
    if ([view1 isKindOfClass:[MyCustomView class]])    
        return NSOrderedDescending;    
    else if ([view2 isKindOfClass:[MyCustomView class]])    
        return NSOrderedAscending;    

    return NSOrderedSame;
}

Then when you want to ensure your custom view remains above all sibling views, send this message to your custom view's superview:

[[myCustomView superview] sortSubviewsUsingFunction:myCustomViewAboveSiblingViewsComparator context:NULL];

Alternatively, you can move this code to the superview itself, and send the message sortSubviewsUsingFunction:context: to self instead.