Short story: we now properly decide whether the sheet is being resized
or scrolled, fixing the bug.
Long story:
Some users report that they can't scroll the forward message sheet
([example report 1][1], [example report 2][2]). This wasn't just a bug
with the forwarding sheet. It was a bug with all subclasses of
`InteractiveSheetViewController`.
When you gesture on the sheet, there are effectively two modes: "resize
the sheet mode", and "scroll the contents" mode. (See
`beginInteractiveTransitionIfNecessary` for a boolean that expresses
this.) The logic is effectively this:
def getMode():
if sheetHeight < maximumSheetHeight:
# Note: there are some other ways to get this mode, e.g. by
# grabbing the handle. But those aren't relevant for this bug.
return "resize the sheet mode"
else:
return "scroll the contents mode"
Unfortunately, there was a bug in how we computed the max sheet height
if that height was larger than the height of the screen (e.g., in
landscape mode or on a shorter device). That bad height caused you to
get into "resize the sheet mode" incorrectly. This fixes that, and does
a few other cleanups.
[1]: https://github.com/signalapp/Signal-iOS/issues/5366
[2]: https://community.signalusers.org/t/beta-feedback-for-the-upcoming-ios-5-44-release/45401/3
Co-Authored-By: Igor Solomennikov <igor@signal.org>
