Bug 51577 - App crash on Multi-touch Tapped on empty and non-empty cell in ListView
Summary: App crash on Multi-touch Tapped on empty and non-empty cell in ListView
Alias: None
Product: Forms
Classification: Xamarin
Component: iOS ()
Version: 2.3.3
Hardware: PC Mac OS
: Normal normal
Target Milestone: ---
Assignee: Paul DiPietro [MSFT]
Depends on:
Reported: 2017-01-17 15:38 UTC by Akshay
Modified: 2017-06-19 19:11 UTC (History)
3 users (show)

Tags: ios
Is this bug a regression?: ---
Last known good build:

Notice (2018-05-24): bugzilla.xamarin.com is now in read-only mode.

Please join us on Visual Studio Developer Community and in the Xamarin and 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 Links.

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.

Related Links:

Description Akshay 2017-01-17 15:38:16 UTC
Application gets crash when tapping without releasing the finger from the available item and on the empty space of list view.

Exception found from Xcode is as below:

<Warning>: Unhandled managed exception:
	Object reference not set to an instance of an object (System.NullReferenceException)
	  at Xamarin.Forms.Platform.iOS.ContextActionsCell+SelectGestureRecognizer.Tapped (UIKit.UIGestureRecognizer recognizer) [0x00013] in C:\BuildAgent2\work\ca3766cfc22354a1\Xamarin.Forms.Platform.iOS\ContextActionCell.cs:666 
	  at UIKit.UITapGestureRecognizer+Callback.Activated (UIKit.UITapGestureRecognizer sender) [0x00000] in /Users/builder/data/lanes/3969/44931ae8/source/xamarin-macios/src/UIKit/UIGestureRecognizer.cs:211 

Adding sample code to re-produce this issue.

Steps to re-produce for attached code:

1. Install the app, and you can see only one cell which has text "notification"
2. Now put one finger on "notification" cell and use another finger to tap on empty cells.

App will get crash immediately with above exception.
Comment 1 Paul DiPietro [MSFT] 2017-02-14 20:07:07 UTC
Your reproduction is missing. Please attach one when you're able if this is still persisting using the latest stable/prerelease.
Comment 2 Akshay 2017-02-23 10:32:29 UTC
Hi Paul,

Yes, I'm still able to reproduce this issue on latest Xamarin.Forms packages. So it would be great if you fix it as soon as possible.

Again how to reproduce this issue on existing code base:

- Update required packages to latest.
- When you see app running, then put your one finger on TableView Cell which has test "notification". Now without removing first finger tap outside of the list view by putting another finger.
- You will be able to observe the crash.

I hope this will help you.
Comment 3 Paul DiPietro [MSFT] 2017-02-23 13:58:18 UTC
Do you have the reproduction project to upload? It's still missing.
Comment 4 Paul DiPietro [MSFT] 2017-06-19 19:11:39 UTC
Because we have not received a reply to our request for more information we are closing this issue. If you are still encountering this issue, please reopen the ticket and attach a project that demonstrates the issue.