How to determine the correct UIScrollView zoomScale with a CATiledLayer

I created a UIScrollView with a CATiledLayer for a 10000x8078 image.

Would I place this image in a UIView the zoomScale is always updated according to the contentSize (respectively the size of the image).

With CATiledLayer the contentSize now varies according to the tiles in use.

How can I now determine the correct zoomScale of the UISrcollView?

Thanks

Solution

What has worked for me, based on the the ZoomingPDFViewer Sample Code, is to keep tabs on the zoom manually the following way in the UIScrollView delegate:

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
{

    scrollView.scrollEnabled = YES;
    // set the new scale factor for the TiledPDFView
    pdfScale *=scale;
        ....