How to detect "Drag Enter" on UIScrollView
Imagine a UIButton and a user who taps somewhere OUTSIDE the button and then slides onto it. If I want the button to detect such touches I can register it for any "Touch Drag Enter" events.
My question: is there some way to achieve the same for a UIScrollView? Ie, I tap somewhere outside the scrollview, drag my finger onto the scrollview and as soon as I enter the scrollviews frame it starts panning? (Because by default it doesn't, I have to start my touch INSIDE the scrollview in order to pan)
Imagine a UIButton and a user who taps somewhere OUTSIDE the button and then slides onto it. If I want the button to detect such touches I can register it for any "Touch Drag Enter" events
Actually, no you can't. A UIControl will not get any of the control events unless the touch started in the control.
And that's for the same reason that you are seeing a similar effect with the scroll view. This is the entire basis of touch delivery on iOS. A touch "belongs" to the view that was initially touched.
After all, the runtime cannot possibly know that you are going to drag into the scroll view...
If you want to do this, you will have to do a custom implementation using -touchesBegan, -touchesMoved, and -touchesEnded
The documentation for the UIResponder class (which all ViewControllers inherit from) that allows you to do this is here.
Hopefully you can figure out what to do from here. :)
As an extra hint, you will also most likely need to use this function
bool contains = CGRectContainsPoint(CGRect rect, CGPoint point);