Swift image zoom

ImageZoom.swift

// The image is originally animated on to the view controller then added to the scroll view.
// So, there might be some animation residue in here.
// Class needs: <UIScrollViewDelegate>

func viewDidLoad() {
    let width = UIScreen.mainScreen().bounds.size.width
    let aspect: CGFloat = width / shotWidth

    var frame = CGRectMake(0, 0, shotWidth * aspect, shotHeight * aspect)
    self.scrollView = UIScrollView(frame: frame)

    self.scrollView!.bounces = false
    self.scrollView!.showsHorizontalScrollIndicator = false
    self.scrollView!.showsVerticalScrollIndicator = false
    self.scrollView!.userInteractionEnabled = true
    self.scrollView!.delegate = self
    self.scrollView!.bouncesZoom = false
    self.scrollView!.scrollsToTop = false
    self.scrollView!.maximumZoomScale = 2.0
    self.scrollView!.minimumZoomScale = 1.0

    self.doubleTap = UITapGestureRecognizer(target: self, action: "zoom:")
    self.doubleTap!.numberOfTapsRequired = 2
    self.doubleTap!.numberOfTouchesRequired = 1
    self.scrollView!.addGestureRecognizer(self.doubleTap!)

    // This was run when the animation is complete
    self.imageView!.removeFromSuperview()
    self.scrollView!.addSubview(self.imageView!)
    self.addSubview(self.scrollView!)
}

func loadImage() {
    // This is run in the callback when the full image has been loaded (image = UIImage)
    self.imageView!.frame = CGRectMake(0, 0, image.size.width, image.size.height)
    self.imageView!.image = image
    self.scrollView!.contentSize = image.size

    var imgwidth = CGFloat(self.bounds.size.width / image.size.width)
    var imgheight = CGFloat(self.bounds.size.height / image.size.height)
    var minZoom: CGFloat = min(imgwidth, imgheight)

    NSLog("image size: %@ / %f", NSStringFromCGSize(image.size), minZoom)

    if (minZoom <= 1) {
        self.scrollView!.minimumZoomScale = minZoom
        self.scrollView!.setZoomScale(minZoom, animated: false)
        self.scrollView!.zoomScale = minZoom
    }
}

// delegates:

func zoom(tapGesture: UITapGestureRecognizer) {
    if (self.scrollView!.zoomScale == self.scrollView!.minimumZoomScale) {
        var center = tapGesture.locationInView(self.scrollView!)
        var size = self.imageView!.image!.size
        var zoomRect = CGRectMake(center.x, center.y, (size.width / 2), (size.height / 2))
        self.scrollView!.zoomToRect(zoomRect, animated: true)
    } else {
        self.scrollView!.setZoomScale(self.scrollView!.minimumZoomScale, animated: true)
    }
}

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