touchesEnded can't be called in chart view?

[ijinliu]

I build a Bar Chart View and the chartView is running as a horizontal scrollview.
And now I want to collect the touchesBegin location and also touchesEnded location, so that I could calculate the distance which the user swipe on the chartView.
I could call touchBegin directly when I touch the chartView, however, I found that I couldn't get touchesEnded called. It will become touchesCancelled when I release the touch.
But when I touch the view outside the chartView, it can be collected.
If there is any solution that I could collect the touchesEnded location when I swipe on the chartView?
Any help is appreciated!! Thanks you first anyway!!

[liuxuan30]

ask on stack overflow. This is beyond chart scope.