added a PixelDataDestroyer to properly clean up the underlying PixelB…

…itmap data buffer

Prototope/Image.swift

@@ -43,11 +43,22 @@ public struct Image {
 public struct PixelBitmap : MutableCollectionType {
     typealias Index = Int
 
+    var data: UnsafeMutablePointer<Pixel>
+    let width: Int
+    let height: Int
+
+    public let startIndex: Int = 0
+
+    public var endIndex: Int { return height * width }
+
+    private let dataDestroyer: PixelDataDestroyer
+
     init(image: Image) {
         width = Int(image.size.width)
         height = Int(image.size.height)
 
         data = UnsafeMutablePointer<Pixel>.alloc(width*height)
+        dataDestroyer = PixelDataDestroyer(data: data, width: width, height: height)
 
         let colorSpace: CGColorSpace = CGColorSpaceCreateDeviceRGB()
         let bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.PremultipliedLast.rawValue)
@@ -57,14 +68,6 @@ public struct PixelBitmap : MutableCollectionType {
 
         CGContextDrawImage(context, CGRect(origin: CGPointZero, size: image.uiImage.size), image.uiImage.CGImage)
     }
-
-    var data: UnsafeMutablePointer<Pixel>
-    let width: Int
-    let height: Int
-
-    public let startIndex: Int = 0
-
-    public var endIndex: Int { return height * width }
 
     public subscript (position: Int) -> Pixel {
         get { return data[position] }
@@ -117,6 +120,22 @@ public struct PixelBitmap : MutableCollectionType {
 
         return newBitmap
     }
+
+    private class PixelDataDestroyer {
+        let pixelDataToCleanUp: UnsafeMutablePointer<Pixel>
+        let width: Int
+        let height: Int
+
+        init(data: UnsafeMutablePointer<Pixel>, width: Int, height: Int) {
+            self.pixelDataToCleanUp = data
+            self.width = width
+            self.height = height
+        }
+
+        deinit {
+            pixelDataToCleanUp.dealloc(width*height)
+        }
+    }
 }