Bug 46039 - listview ItemSource not updating
Summary: listview ItemSource not updating
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 2.3.2
Hardware: PC Mac OS
: --- normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2016-10-27 15:05 UTC by Andrew
Modified: 2017-06-09 17:08 UTC (History)
5 users (show)

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

sample (57.82 KB, application/zip)
2016-10-27 15:06 UTC, Andrew

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Description Andrew 2016-10-27 15:05:42 UTC
Xamarin Forms version:

Android works as expected. iOS not refreshing ItemSource after update.

Run Sample.

Click "Write Tab"
Click "Write" Button a few times

Go back to the "Log" Tab.  The listview should display items.
Comment 1 Andrew 2016-10-27 15:06:06 UTC
Created attachment 18250 [details]
Comment 2 Andrew 2016-10-27 15:08:54 UTC
The workaround is to add this:  

list.ItemsSource = null;      // first set to null.  should not be needed
list.ItemsSource = App.Log;
Comment 3 adrianknight89 2016-11-01 08:39:00 UTC
I'm not sure why this was confirmed. Was this regression?

The issue is that App.Log is not changing its reference but its content. List<string> has no concept of individual items updating. Use an ObservableCollection instead.

public static ObservableCollection<string> Log;
Comment 4 adrianknight89 2016-11-01 08:41:00 UTC
Actually, since you said Android works, then this is probably a bug. I'll try to look at it again tomorrow.
Comment 5 Andrew 2016-11-01 16:16:23 UTC
I was doing a test and expected it to update like Android without first setting listview.Itemsource = null. I just rebound it on appear.
Comment 6 adrianknight89 2016-11-08 01:32:52 UTC
@Andrew, this does not work for me on AppCompat either. You said it's working on Android, but I can't duplicate it. Perhaps, try uploading a screencast showing us it's working on Android.

As I said earlier, you should use ObservableCollection instead which implements INotifyCollectionChanged and INotifyPropertyChanged.
Comment 7 Paul DiPietro [MSFT] 2017-06-09 17:08:58 UTC
This is not a bug. Using an ObservableCollection lets it function as expected.