Zoom out on large UIImageView within an UIScrollView

Question

Case: I have a simple piece of code for displaying/zooming/scrolling a large image in an UIImageView->UIScrollView. In this UIScrollView content I want to place buttons to create clickable areas.

Issue: When I zoom in the quality remains proper but, when I zoom out to the highest posible level than the image is getting dotted and some lines aren't visible anymore.

Tried: I tried to regenerate the UIImage with Interpolation Quality on kCGInterpolationHigh and tried to change the size of the image after every zoom change. As you might aspect, no results jet.

Answer 1

I suggest you use a CATiledLayer as the backing layer, as demonstrated by Apple's PhotoScroller sample app. This allows you to prebuild the scaled versions, meaning you can precisely control the interpolation quality with Photoshop/ImageMagick/GIMP etc, rather than relying on UIScrollView's built-in scaling.