[Metaballs] The ViewController is the bridge between the Field and the Renderer

Metaballs/ViewController.swift

@@ -7,21 +7,62 @@
 //
 
 import Cocoa
+import MetalKit
+import MetaballsKit
 
-class ViewController: NSViewController {
+class ViewController: NSViewController, RendererDelegate {
+    private var field = Field(size: CGSize()) {
+        didSet {
+            field.size = metalView.drawableSize
+        }
+    }
+
+    private var renderer: Renderer!
+
+    private var metalView: MTKView! {
+        return self.view as! MTKView
+    }
 
     override func viewDidLoad() {
         super.viewDidLoad()
 
-        // Do any additional setup after loading the view.
+        guard let metalView = metalView else {
+            view = newErrorView()
+            print("self.view should be an MTKView; got \(type(of: self.view)) instead")
+            return
         }
 
-    override var representedObject: Any? {
-        didSet {
-        // Update the view, if already loaded.
-        }
+        do {
+            renderer = try Renderer(view: metalView, field: field)
+        } catch let e {
+            print("\(e)")
+            view = newErrorView()
+            return
         }
 
+        metalView.delegate = renderer
+    }
 
+    override func viewWillAppear() {
+        super.viewWillAppear()
+        renderer.mtkView(metalView, drawableSizeWillChange: metalView.drawableSize)
+    }
+
+    private func newErrorView() -> NSView {
+        let view = NSView()
+        view.layer?.backgroundColor = NSColor.red.cgColor
+        return view
+    }
+
+    // MARK: - RendererDelegate
+
+    var renderSize: CGSize {
+        get {
+            return field.size
+        }
+        set {
+            field.size = newValue
+        }
+    }
 }