How to draw NSRect in a new location - swift

Question

I am a newbie to Swift coding
Below is a custom view class:
class MyView: NSView {
var xloc = 0.0
var yloc = 0.0
var width = 400.0
var height = 200.0
var myRect = NSRect(x: 0.0, y: 0.0, width: 400.0, height: 200.0)
...
override func draw(_ dirtyRect: NSRect) {
let myColor = NSColor(red: 1.0, green: 1.0, blue: 1.0, alpha: self.alpha)
myColor.setFill()
dirtyRect.fill()
self.myRect = NSRect(x: self.xloc, y: self.yloc, width: self.width, height: self.height)
self.setNeedsDisplay(myRect)
self.myRect.fill(using: NSCompositingOperation.clear)
}
The view controller has a keyDown handler as follows:
override func viewDidLoad() {
super.viewDidLoad()
view.window?.backgroundColor = NSColor.white
NSEvent.addLocalMonitorForEvents(matching: .keyDown) {
self.keyDown(with: $0)
return $0
}
}
override func keyDown(with event: NSEvent) {
let theView = self.view as! MyView
if event.keyCode == 126 {
NSLog("Increasing Y coordinate")
theView.yloc = theView.yloc + 10
self.view.display()
}
}
Below is the AppDelegate.swift's content:
func applicationDidFinishLaunching(_ aNotification: Notification) {
let window = NSApplication.shared.windows.first
window?.isOpaque = false
window?.backgroundColor = NSColor.clear
window?.ignoresMouseEvents = true
window?.toggleFullScreen(self)
window?.collectionBehavior = NSWindow.CollectionBehavior.fullScreenPrimary
let screenFrame = NSScreen.main?.frame
window?.setFrame(screenFrame!, display: true)
let myView = MyView()
window?.contentView = myView
}
The rectangular hole is seen on the screen initially
The above handler is called whenever I press the up arrow key. The self.view.display() in turn calls the draw() method on the view. But the NSRect is not drawn in the new position
Not sure what is wrong