CODEWITHSUNDEEP
iosswiftuiscrollview
Kashif
Kashif

Reputation: 4632

UIScrollView zoomScale inconsistent

Below code runs as expected the first time I pick an image from camera roll. Image is zoomed out propery to fit in scrollView. But when I run it again to repick an image and pick the same image again, it gets zoomed to 1.0 scale. Cannot figure out what I need to reset to make it work the same everytime. Any ideas?

func imagePickerController(picker: UIImagePickerController!, didFinishPickingImage image: UIImage!, editingInfo: [NSObject : AnyObject]!) {

    scrollView.contentSize = CGSize(width: 0, height: 0)
    picView.image = nil
    picView.frame = CGRect(x: 0, y: 0, width: 0, height: 0)
    picView.removeFromSuperview()
    self.dismissViewControllerAnimated(true, completion: nil)
    scrollView.addSubview(picView)

    scrollView.contentSize = image.size

    let scaleWidth = scrollView.frame.size.width / scrollView.contentSize.width //image.size.width
    let scaleHeight = scrollView.frame.size.height / scrollView.contentSize.height //image.size.height
    let minScale = min(scaleWidth, scaleHeight)
    scrollView.minimumZoomScale = minScale
    scrollView.maximumZoomScale = 1.0
    scrollView.zoomScale = minScale
}

Upvotes: 2

Views: 1383

Answers (1)

matt
matt

Reputation: 535284

I think you've already figured this out, but I'll just fill in what might be the missing piece of the puzzle. How does zooming actually work? As I say in my book:

The scroll view zooms by applying a scaling transform to the scalable view... Moreover, the scroll view is concerned to make scrolling continue to work correctly; ... therefore, the scroll view automatically scales its own contentSize to match the current zoomScale.

So you need to remove that transform before you start playing with the content size. Thus it might be sufficient to reset the zoomScale to 1 up front, before you go swapping out the image view.

Even better, why not leave the image view there? You seem to be doing a lot of unnecessary work in your routine; why not think of this as a scroll view with an image view content view, where what gets swapped out is only the image?

Finally, why not use auto layout? That way, the image's size automatically becomes the image view's size, and the image view's size automatically becomes the scroll view's content size.

Upvotes: 4

Related Questions