moving data between classes in swift 4 - ios

Question

I'm new to swift and am making an graphing app with two views where one has a text field to enter data and the other has a view to display the data. I've got the data as two arrays of doubles in my ViewController class, but I can't move the data to the class of UIView where I want to draw to the view it because it does not inherit the arrays. I've tried accessor methods but that hasn't changed anything.
Here is the class that contains xValues and yValues
class ViewController: UIViewController {
#IBOutlet var DataEntry: UITextView!
var xValues = Array<Double>()
var yValues = Array<Double>()
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
//the xValues and yValues arrays are filled when the view changes on the press of a button
}
public func getXCord() -> Array<Double>{
return xValues
}
public func getYCord() -> Array<Double>{
return yValues
}
}
Here is the class I want them delivered to. I'm getting an error when initializing xCords and yCords to ViewController.getXCord() and ViewController.getYCord() respectively.
class GraphView: UIView{
var points: [Points] = []
var xCords: Array<Double> = ViewController.getXCord()
var yCords: Array<Double> = ViewController.getYCord()
var position = CGPoint(x: 0,y: 0)
}

Answer 1

You are doing this the complete opposite way.
In the MVC pattern, the view, your GraphView class, should never directly talk to the controller. Instead, the view should use a delegate and/or a datasource to communicate with the controller.
Your view should have a GraphViewDatasource:
protocol GraphViewDatasource : class {
func xValues(inGraph: GraphView) -> [Double]
func yValues(inGraph: GraphView) -> [Double]
}
// in GraphView
weak var datasource: GraphViewDatasource?
func reloadData() {
guard let datasource = self.datasource else { return }
xValues = datasource.xValues(inGraph: self)
yValues = datasource.yValues(inGraph: self)
// redraw the graph...
}
Your controller should implement GraphViewDatasource:
class ViewController: UIViewController, GraphViewDatasource {
func xValues(inGraph: GraphView) -> [Double] { return self.xValues }
func yValues(inGraph: GraphView) -> [Double] { return self.yValues }
}
and set self as the data source of the graph view:
let graph = GraphView(frame ...)
self.view.addSubView(graph)
graph.datasource = self
graph.reloadData()

Answer 2

You need to pass xCoords and yCoords to GraphView from ViewController.
First, initialize xCoords and yCoords with empty array:
class GraphView: UIView{
var points: [Points] = []
var xCords: Array<Double> = []
var yCords: Array<Double> = []
var position = CGPoint(x: 0,y: 0)
}
Than pass it from ViewController:
class ViewContoller: UIViewController {
#IBOutlet var graphView: GraphView!
override func viewDidLoad() {
super.viewDidLoad()
graphView.xCoords = self.xCoords
graphView.yCoords = self.yCoords
}
}