crop UIImage to the shape of a rectangular overlay - Swift - ios

Question

I am pretty new to Swift.
I intend to draw a rectangle and capture the image in the rectangular overlay.
I drew a transparent image over the camera.
let imagePicker = UIImagePickerController()
imagePicker.delegate = self
imagePicker.sourceType = UIImagePickerControllerSourceType.Camera
imagePicker.mediaTypes = [kUTTypeImage as String]
imagePicker.allowsEditing = true
var overlayedImageView: UIImageView = UIImageView(image: UIImage(named: "transparent.png"))
var cgRect: CGRect = CGRect(x: 200, y: 50, width: 100, height: 400)
overlayedImageView.frame = cgRect
imagePicker.cameraOverlayView = overlayedImageView
self.presentViewController(imagePicker, animated: true,
completion: nil)
This is what i do after i capture the image
func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
let mediaType = info[UIImagePickerControllerMediaType] as! String
self.dismissViewControllerAnimated(true, completion: nil)
if mediaType == (kUTTypeImage as String) {
let image = info[UIImagePickerControllerOriginalImage]
as! UIImage
imageView.image = cropToBoundsNew(image)
if (newMedia == true) {
UIImageWriteToSavedPhotosAlbum(image, self,
"image:didFinishSavingWithError:contextInfo:", nil)
} else if mediaType == (kUTTypeMovie as String) {
// Code to support video here
}
}
}
My Problem is the quality of the image diminishes
func cropToBoundsNew(image: UIImage) -> UIImage {
let contextImage: UIImage = UIImage(CGImage: image.CGImage!)
let contextSize: CGSize = contextImage.size
let rect: CGRect = CGRectMake(200, 50, 100, 400)
let imageRef: CGImageRef = CGImageCreateWithImageInRect(contextImage.CGImage, rect)!
let image: UIImage = UIImage(CGImage: imageRef, scale: image.scale, orientation: image.imageOrientation)
return image
}