touchesMoved.swift

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)
        
        if state == .failed || touches.count != 2 {
            return
        }
        
        let window = view?.window
        let arrayTouches = Array(touches)
        
        // First finger
        if let loc = arrayTouches.first?.location(in: window) {
            firstTouchedPoints.append(loc)
            state = .changed
        }

        // Second finger
        if let loc = arrayTouches.last?.location(in: window) {
            secondTouchedPoints.append(loc)
            state = .changed
        }
    }