Prevent scroll view content from being locked

[gunnarsson]

I posted a comment on #587 earlier, but I'm not sure whether anybody will notice, so I'll post here as well. Sorry about that.

The fix for the issue in question broke a piece of code of mine. I wonder if anybody could help me adjust it to work well with more modern versions of FloatingPanel.

Here's what I want to achieve: If the user expands the panel to .full state and scrolls down to the bottom of the panel, and then drags the handle down to move it to .half state, the content should scroll to top. Otherwise the user has to expand the panel again, manually scroll to top, and then pull it down to .half again, which is tedious.

Here's what I used to do:

    func floatingPanelDidChangeState(_ fpc: FloatingPanelController) {
        guard let detailsView = fpc.contentViewController as? PlaygroundDetailViewController else {
            return
        }
        
        // If the content is scrolled down, restore it to the top when the state of the panel
        // changes, to prevent an awkward state where you have to move the panel up to full
        // in order to be able to scroll the content up again
        if fpc.state == .tip || fpc.state == .half {
            DispatchQueue.main.async {
                detailsView.scrollView.setContentOffset(CGPoint.zero, animated: fpc.state == .half)
            }
        }
    }

The new pinning of the scroll position immediately sets the content offset back to the original position. I can make it work by delaying the async call an arbitrary amount of time, but that feels very hacky. Given this new functionality, how can I achieve the behavior I'm after? Can I prevent the pinning, or make my contentOffset adjustment in a more suitable callback?

[gunnarsson]

I created #647 to let the user of the library decide on this functionality.