What I'm trying to achieve is actually a little different than what you've posted.
Here is the screenshot from my question on Stackoverflow again.
Yes, it looks exactly like the code you've shown above. The difference is, that I need to synchronise all charts on user interaction. For that to work I need a blank canvas the same size as the ScrollView that detects pan/pinch/tap/longpress and so on. That way, the user only interacts with a single canvas and doesn't need to touch exactly within the frame of a ShinobiChart. I hope you get what I'm trying to achieve here.
Take a chart like the following;
Remove the range selector at the bottom (that will be placed outside of the ScrollView) and what you've got there are two charts, the main line chart and the volume indicator at the bottom. In order to pan/zoom both charts simultaneously, you'd have to link them by code and add gestures recognizers to each chart which will then set the range of the other chart as well.
That works, but you'd have to hit each chart in it's frame exactly, which is just a bad user experience. The user wants to touch the entire thing (the combined view area consisting of n charts) and just pinch, pan, without the need to put both fingers in chart a or b.
That's why I need some sort of touch interceptor that overlays the entire UIScrollView (not the content area, but the visible area) and intercept all touches for that given frame.
Those touches would have to get forwarded to the main chart, which in turn updates the ranges of the indicator charts.
I hope that's understandable. In case there are any questions left, please let me know.