Added helper methods for CALayer.

PixelImage/UIKit.swift

@@ -1,3 +1,5 @@
+// TODO: Unite UIView and CALayer extensions under a common protocol
+
 import UIKit
 
 func - (left: CGPoint, right: CGPoint) -> CGVector {
@@ -139,6 +141,79 @@ extension UIView {
     }
 }
 
+extension CALayer {
+    var origin: CGPoint {
+        get {
+            return frame.origin
+        }
+        set {
+            frame.origin = newValue
+        }
+    }
+
+    var size: CGSize {
+        get {
+            return frame.size
+        }
+        set {
+            frame.size = newValue
+        }
+    }
+
+    var width: CGFloat {
+        get {
+            return frame.width
+        }
+        set {
+            frame.size = CGSize(width: newValue, height: height)
+        }
+    }
+
+    var height: CGFloat {
+        get {
+            return frame.height
+        }
+        set {
+            frame.size = CGSize(width: width, height: newValue)
+        }
+    }
+
+    var middle: CGPoint {
+        get {
+            return CGPoint(x: origin.x + width / 2, y: origin.y + height / 2)
+        }
+        set {
+            origin = CGPoint(x: newValue.x - width / 2, y: newValue.y - height / 2)
+        }
+    }
+
+    var midX: CGFloat {
+        get {
+            return middle.x
+        }
+        set {
+            middle = CGPoint(x: newValue, y: midY)
+        }
+    }
+
+    var midY: CGFloat {
+        get {
+            return middle.y
+        }
+        set {
+            middle = CGPoint(x: midX, y: newValue)
+        }
+    }
+}
+
 let screenRect = UIScreen.mainScreen().bounds
 let screenWidth = screenRect.size.width
 let screenHeight = screenRect.size.height
+
+func * <T: Numeric>(vector: CGVector, scalar: T) -> CGVector {
+    return CGVector(dx: vector.dx * CGFloat(scalar.toDouble), dy: vector.dy * CGFloat(scalar.toDouble))
+}
+
+func + (point: CGPoint, vector: CGVector) -> CGPoint {
+    return CGPoint(x: point.x + vector.dx, y: point.y + vector.dy)
+}