[saver] DOES NOT BUILD, but I need to go to bed -_-

Quickly build a Swift version of a ScreenSaverView and throw some Metal at it.
Having trouble getting the RendererDelegate protocol satisfied.

MetaballsSaver/MetaballsSaverView.swift

@@ -0,0 +1,97 @@
+//
+//  MetaballsSaverView.swift
+//  Metaballs
+//
+//  Created by Eryn Wells on 8/16/17.
+//  Copyright © 2017 Eryn Wells. All rights reserved.
+//
+
+import Foundation
+import MetaballsKit
+import MetalKit
+import ScreenSaver
+
+class MetaballsSaverView: ScreenSaverView, RendererDelegate {
+    private static func defaultParameters() -> Parameters {
+        var p = Parameters()
+        let defaults = UserDefaults.standard
+        let style = defaults.colorStyle ?? .gradient2Horizontal
+        p.colorStyle = style
+        let color0 = defaults.color0 ?? Float4(0.50, 0.79, 1, 1)
+        p.color0 = color0
+        let color1 = defaults.color1 ?? Float4(0.88, 0.50, 1, 1)
+        p.color1 = color1
+        return p
+    }
+
+    public var metalView: MTKView
+
+    public var field: Field {
+        didSet {
+            field.size = Size(size: metalView.drawableSize)
+        }
+    }
+
+    internal var renderer: RendererDelegate
+
+    override init?(frame: NSRect, isPreview: Bool) {
+        let params = MetaballsSaverView.defaultParameters()
+        field = Field(parameters: params)
+
+        metalView = MTKView()
+        metalView.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(metalView)
+        NSLayoutConstraint.activate([
+            metalView.topAnchor.constraint(equalTo: topAnchor),
+            metalView.leftAnchor.constraint(equalTo: leftAnchor),
+            metalView.bottomAnchor.constraint(equalTo: bottomAnchor),
+            metalView.rightAnchor.constraint(equalTo: rightAnchor),
+        ])
+
+        do {
+            renderer = try Renderer(delegate: self)
+        } catch let e {
+            fatalError("\(e)")
+        }
+
+        super.init(frame: frame, isPreview: isPreview)
+    }
+    
+    required init?(coder: NSCoder) {
+        let params = MetaballsSaverView.defaultParameters()
+        field = Field(parameters: params)
+
+        metalView = MTKView()
+        metalView.translatesAutoresizingMaskIntoConstraints = false
+        addSubview(metalView)
+        NSLayoutConstraint.activate([
+            metalView.topAnchor.constraint(equalTo: topAnchor),
+            metalView.leftAnchor.constraint(equalTo: leftAnchor),
+            metalView.bottomAnchor.constraint(equalTo: bottomAnchor),
+            metalView.rightAnchor.constraint(equalTo: rightAnchor),
+        ])
+
+        do {
+            renderer = try Renderer(delegate: self)
+        } catch let e {
+            fatalError("\(e)")
+        }
+
+        super.init(coder: coder)
+    }
+
+    override func animateOneFrame() {
+
+    }
+
+    // MARK: - RendererDelegate
+
+    public var renderSize: Size {
+        get {
+            return field.size
+        }
+        set {
+            field.size = newValue
+        }
+    }
+}