Quickly apply a 1-pixel debugging border to NSView instances.

NSView+DebugBorder.swift

extension NSView {
    
    var debugBorder: NSColor? {
        set {
            guard let newValue = newValue else {
                self.layer?.borderColor = nil;
                self.layer?.borderWidth = 0;
                return;
            }
            
            self.wantsLayer = true;
            self.layer?.borderColor = newValue.cgColor;
            self.layer?.borderWidth = 1;
        }
        
        get {
            guard let color = self.layer?.borderColor else {
                return nil;
            }
            
            return .init(cgColor: color)
        }
    }
    
}