Really, really big UIScrollViews

Question

Hi Everyone,

I'm trying to make a level-of-detail line chart, where the user can zoom in/out horizontally by using two fingers, and grow the contentSize attribute of the the UIScrollView field. They can also scroll horizontally to shift left or right and see more of the chart (check any stock on Google Finance charts to get an idea of what I'm talking about). Potentially, the scroll view could grow to up to 100x its original size, as the user is zooming in.

My questions are: - Has anyone had any experience with UIScrollViews that have such large contentSize restrictions? Will it work? - The view for the scroll view could potentially be really huge, since the user is zooming in. How is this handled in memory?
- Just a thought, but would it be possible to use UITableViewCells, oriented to scroll horizontally, to page in/out the data?

This is kind of an open ended question right now - I'm still brainstorming myself. If anyone has any ideas or has implemented such a thing before, please respond with your experience. Thanks!

Answer 1

I have something similar, although probably not to the size your talking about. The UIScrollView isn't a problem. The problem is that if you're drawing UIViews on it (rather than drawing lines yourself) UIViews that are well, well off the screen continue to exist in memory. If you're actually drawing the lines by creating your own UIView and responding to drawRect, it's fine.

Assuming that you're a reasonably experienced programmer, getting a big scroll view working that draws pars of the chart is only a days work, so my recommendation would be to create a prototype for it, and run the prototype under the object allocations tool and see if that indicates any problems.

Sorry for the vagueness of my answer; it's a brainstorming question