I have an iOS app which boils down to the following:

* A view controller which implements all the `UIScrollViewDelegate` methods.
* A customised `UIImageView` which is the view returned by `viewForZoomingInScrollView` in the first view controller.

In the `drawRect` method of the customised `UIImageView` I overlay some text at various positions on the image, the text can be at various sizes and angles, constrained by a rectangle defined by points on the image. So the co-ordinate system is all relative to the image associated with the `UIImageView`.

Sometimes the text is having to be rendered into areas that are far too small to allow the text to be readable at the default zoom level.

When I zoom in, however, this doesn't make the text any more readable as the text was rendered on the original `UIImageView` at the font size appropriate for the bounds it was given. 

What I'd like is some way to redraw this text, in the correct location still, at a proportionally larger font size when zoomed in. Is this possible, and how would I do it?