Notice (2018-05-24): bugzilla.xamarin.com is now in
Please join us on
Visual Studio Developer Community and in the
Mono organizations on
GitHub to continue tracking issues. Bugzilla will remain
available for reference in read-only mode. We will continue to work
on open Bugzilla bugs, copy them to the new locations
as needed for follow-up, and add the new items under Related
Our sincere thanks to everyone who has contributed on this bug
tracker over the years. Thanks also for your understanding as we
make these adjustments and improvements for the future.
Please create a new report on
Developer Community or GitHub with
your current version information, steps to reproduce, and relevant error
messages or log files if you are hitting an issue that looks similar to
this resolved bug and you do not yet see a matching new report.
Created attachment 18002 [details]
Example project that reproduces the bug.
Sometimes, when you add or remove items from a ListView, the Header element is given an incorrect size and disappears. I'm not exactly sure what sequence of events causes it, but I have attached a project that reproduces based on the UI in my project.
The project represents a page that is performing some long operation that will produce a set of items for the ListView. In preparation, the Header element of the ListView is set up. A 3-second Task inside the RouteDetailsView constructor simulates the completion of that long-running task and population of items. When the items are populated, the header disappears.
I've done some debugging via Immediate/Watch and discovered the Label in the header is being given a Height of -1. I've confirmed this with Label-derived classes that override OnSizeAllocated(). My understanding is you should NEVER pass a -1 for any size parameter in XF layout, so something's probably going haywire in the renderer for the ListView.
This is an iOS-specific bug I have witnessed on 9.3.4 and iOS 10 devices and simulators. It does not reproduce in any Android cases I tried. I'm using Xamarin Studio 6.1.1 with Xamarin.iOS 10.0.1.10. I first experienced the bug in Xamairn.Forms 18.104.22.16824, but I have also reproduced it in 22.214.171.124.
Please follow the issue on GitHub for updates. Thank you.