OSX Swift , Draw a simple line with a push of a button - macos

Question

Have looked a lot for this but nothing found to match.
Real simple I want to draw a line buy a push of a button.
I have a class which is from NSView to do the drawing, this monitors a var and if it changes to redraw the view.
I can get the mouse click to call the view by changing the value and it draws just fine. But I cant get the button to work. It calls the drawing method but the view is not updated ???
I know its got to be something simple, but I just cannot find it.
Thanks in advance.
Below is my View class and View Controller.
//
// LineDrawer.swift
// TestDraw3
//
// Created by Colin Wood on 21/04/17.
// Copyright © 2017 Colin Wood. All rights reserved.
//
import Cocoa
class LineDrawer : NSView {
// Vars
var newLinear = NSBezierPath()
public var QQ: Int = 0 { // every time QQ changes redraw information in QQ
didSet{
boom() // drawing method
}
}
// Methods
override func draw(_ dirtyRect: NSRect) {
NSColor.red.set()
newLinear.lineWidth = 5
newLinear.lineCapStyle = NSLineCapStyle.roundLineCapStyle
newLinear.stroke()
}
func boom(){ // draw a simple line
Swift.print("In BooM")
Swift.print(QQ)
let lastPt = NSPoint(x: QQ, y: 1)
newLinear.move(to: lastPt)
let newPt = NSPoint(x: QQ, y: 50)
newLinear.line(to: newPt)
needsDisplay = true
}
override func mouseDown(with theEvent: NSEvent) {
QQ = QQ + 7 // just add 7 so you can see it being drawn after didSet
}
}
//
// ViewController.swift
// TestDraw3
//
// Created by Colin Wood on 15/04/17.
// Copyright © 2017 Colin Wood. All rights reserved.
//
import Cocoa
class ViewController: NSViewController {
// Vars
#IBOutlet weak var textField: NSTextField!
// Methods
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
#IBAction func button(_ sender: Any) {
let v = LineDrawer()
v.QQ = 300 // change QQ to call didSet
}
}

Answer 1

You need to add your LineDrawer as a subview. A good place, to add it, is in the viewDidLoad method:
private var line: LinerDrawer!
override func viewDidLoad() {
super.viewDidLoad()
line = LinerDrawer()
line.frame = NSMakeRect(0, 0, 200, 200)
line.QQ = 300
line.isHidden = true
view.addSubview(line)
}
And then finally show it when you hit the button:
#IBAction func button(_ sender: Any) {
line.isHidden = false
}
You still need to work out the correct frame for your LineDrawer view.