IOS drag and drop between scroll views

Question

So here is the catch. I have two Scroll Views, one is filled with 10 odd subviews, that are basically like playing cards (custom class views). I want to be able to drag and drop some of these views to the empty scroll bar that i have.

There are many different views in between these two scroll views. So i want to show the view being actually dragged from one view and being placed in the other scroll view. How do i achieve this.

I know i have to use touches, but if anyone can whip up a quick example, i'll be greatful. Thanks.

Answer 1

Its very easy. ScrollView is like any other view so it's basically drag and drop a view from one superview to another superview.

Your hierarchy is the following: You want to drag and drop a view V from a view A to a view B. That means that when you start D&D, V is subview of A and when you finish, V is subview of B. A and B must have a common superview S.

Steps: 0/ Your touch recognizer must be on S, not on A or B.

1/ User taps on V. You remove it from A and add it to S on the same position (UIView has methods to transform position from a view to another view).
2/ User drags V to B. You change V's position in S.
3/ User drops V. If it's close enough to B, insert it to B (transforming position S->B) and animate the difference between positions. If it's still close to A, animate it back to A. If it's somewhere between A and B you can either insert it to the nearest one or let it stay there and block all other user interaction until user tap V again and drags it into A or B.