ImageCrop

class ImageCropViewController: UIViewController, UIScrollViewDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    @IBOutlet var scrollView: UIScrollView?
    var avatarImage: UIImage?
    var avatarImageFrame: CGRect?

    var imageView = UIImageView()

    @IBOutlet var scrollViewHeightConstraint: NSLayoutConstraint!
    @IBOutlet var scrollViewTopConstraint: NSLayoutConstraint!
    override func viewDidLoad() {
        super.viewDidLoad()

        scrollView!.delegate = self
        imageView.frame = CGRectMake(0, 0, (scrollView?.frame.width)!, (scrollView?.frame.height)!)

        if let validImage = self.avatarImage {
            self.imageView.image = validImage
            imageView.contentMode = .Center
            imageView.frame = avatarImageFrame!
        }
        imageView.userInteractionEnabled = true

        scrollView?.addSubview(imageView)

        scrollView?.contentSize = (avatarImage?.size)!
        let scrollViewFrame = scrollView?.frame
        let scaleWidth = (scrollViewFrame?.size.width)! / (scrollView?.contentSize.width)!
        let scaleHeight = (scrollViewFrame?.size.height)! / (scrollView?.contentSize.height)!

        let minScale = min(scaleHeight, scaleWidth)

        scrollView?.minimumZoomScale = minScale
        scrollView?.maximumZoomScale = 1
        scrollView?.zoomScale = minScale

        centerScrollViewContents()
    }

    func centerScrollViewContents() {
        let boundsSize = scrollView?.bounds.size
        var contentsFrame = imageView.frame

        if contentsFrame.size.width < boundsSize?.width {
            contentsFrame.origin.x = ((boundsSize?.width)! - contentsFrame.size.width) / 2
        } else {
            contentsFrame.origin.x = 0
        }

        if contentsFrame.size.height < boundsSize?.height {
            contentsFrame.origin.y = ((boundsSize?.height)! - contentsFrame.size.height) / 2
        } else {
            contentsFrame.origin.y = 0
        }

        imageView.frame = contentsFrame
    }

    func scrollViewDidZoom(scrollView: UIScrollView) {
        centerScrollViewContents()
    }

    func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
        return imageView
    }

    @IBAction func cropTheImage(sender: AnyObject) {
        UIGraphicsBeginImageContextWithOptions((scrollView?.bounds.size)!, true, UIScreen.mainScreen().scale)

        let offset = scrollView?.contentOffset
        CGContextTranslateCTM(UIGraphicsGetCurrentContext(), -(offset?.x)!, -offset!.y)
        scrollView!.layer.renderInContext(UIGraphicsGetCurrentContext()!)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
    }
}