call a func in NSWindowController from custom class for an NSView - macos

Question

I have a "sheet" as NSWindowController in Swift, for OS X. I placed an NSView on the sheet, with a custom controller in a class called CustomView. Everything I do on the sheet and in the custom view controller works fine.
class MySheet: NSWindowController {
//...
}
class CustomView: NSView {
override func drawRect(dirtyRect: NSRect) {
super.drawRect(dirtyRect) {
// Draw some things...
}
}
override func mouseDown(theEvent: NSEvent) {
// Change text on a label (or whatever) in MySheet()
}
}
Now I need to respond to user input in the CustomView, specifically, a mouse click on the view, and modify a label (or other control) back in MySheet(). This has to be very simple, but I don't know how to do it. The biggest stumbling block I have is that I don't have an instance of MySheet(); it is hidden in the way the system works. I can call back to a static func in MySheet(), but that won't let me change a label or other control through an #IBOutlet.
I know the above is a most likely a naive question, but would appreciate any help toward a solution.

Answer 1

Of course (!), this problem is supposed to be solved using a delegate, and when it is set up correctly it works fine. So I have like this:
protocol ClickableCurves {
func clickedOnCurve(index: Int)
}
class MySheet: NSWindowController, ClickableCurves {
private let lineColorCount = 16
func clickedOnCurve(index: Int) {
Swift.print("came back as \(index)")
}
override func windowDidLoad() {
super.windowDidLoad()
(curveView as! DefaultCurveAttrView).delegate = self
}
#IBOutlet weak var curveView: NSView!
}
class DefaultCurveAttrView: NSView {
var delegate: ClickableCurves? = nil
override func drawRect(dirtyRect: NSRect) {
super.drawRect(dirtyRect)
}
override func mouseDown(theEvent: NSEvent) {
let frameRelWindow = self.convertRect(bounds, toView: nil)
let x = theEvent.locationInWindow.x - frameRelWindow.origin.x
let y = theEvent.locationInWindow.y - frameRelWindow.origin.y
let xm = bounds.width / 10
let dy = bounds.height / CGFloat(lineColorCount + 1)
var yc: CGFloat = dy / 2
if x >= xm && x <= 9 * xm {
for i in 1 ... lineColorCount {
yc += dy
if yc > y || i == lineColorCount {
if delegate != nil {
delegate!.clickedOnCurve(i - 1)
}
break
}
}
}
}
}