QIOSFileEngineAssetsLibrary: bail out early on non-existing dirs

QFileSelector::selectionHelper walks through the list of selectors
(on iOS, on my phone it's ("ios", "iOS", "en_NO", "unix", "darwin")),
creating paths and testing QDir::exists. This ends up in asset
file engine trying to load asset for something like:
"assets-library://assets/+iOS" etc. ALAssetsLibrary -assetForUrl:
returns nil for such url and we start iterating through the assets
library. On my phone (e.g.) this takes about ~6 seconds (to iterate
through pictures/videos I have), so the image picker is dismissed
~30 seconds after an image was actually selected in a picker view,
making an impression it's completely broken. Bail out early
on such url, we know we'll fail (with AssetsLibrary giving a warning
about invalid asset with UUID(null).

Pick-to: 6.5
Fixes: QTBUG-109120
Change-Id: Ia302f4151e3aade830e647a8a260479df2b29d4b
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

0 files changed, 0 insertions, 0 deletions