Bug 27845 - ItemAppearing event is raised before Item actually appears on iOS
Summary: ItemAppearing event is raised before Item actually appears on iOS
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 1.4.0
Hardware: PC Windows
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2015-03-10 18:35 UTC by Martin Booth
Modified: 2016-04-08 18:52 UTC (History)
8 users (show)

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

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Description Martin Booth 2015-03-10 18:35:24 UTC
When HasUnevenRows is set to true on iOS, the ItemAppearing event fires for all items in the list even if they haven't appeared (presumably because they're loaded in order to measure them)

The problem is though that this breaks my infinite scrolling which I think is the main usecase for the ItemAppearing event.

I think the bug is basically the same as 21153, except that it only occurs if HasUnevenRows = true.
Comment 1 Subha 2015-04-06 09:20:49 UTC
Workaround is to set ListView.RowHeight and also set HasUnevenRow to false - http://forums.xamarin.com/discussion/35604/listview-ios-hasunevenrows-true-and-observablecollection
Comment 2 Rui Marinho 2015-05-18 12:38:20 UTC
I can confirm that ItemAppearing is fired for items that didn't appear if we set height on a cell to be bigger than 44, but i didn't get the event to fire for all items of the list, can you provide your sample use case to help us better figure the issue. 
Comment 4 Jason Smith [MSFT] 2016-04-08 18:52:53 UTC
Thank you for taking the time to submit this report. After reviewing the description of this bug, we believe it no longer affects the current version of Xamarin.Forms. If you are still experiencing the issue after updating your packages, please reopen this report with an attached reproduction.
For your convenience, we have created some reproduction best practices viewable here: https://gist.github.com/jassmith/92405c300e54a01dcc6d

Warm regards,
Xamarin Forms Team