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Duplicated
Last Updated: 07 Apr 2020 09:00 by ADMIN
n/a
Created on: 02 Oct 2019 03:29
Category: TreeView
Type: Bug Report
1
[iOS] TreeView scrolling issue when showing expanded items

Scrolling a TreeView with expandable items on iOS causes items to randomly change position in the control and prevent items from being selected.
This renders the control unusable on iOS when expandable items are present.

I've attached a basic project that demonstrates the issue.
The project just needs the latest Telerik binaries added to it. They were too large to include.

I believe this is the same issue Martin was experiencing in the comments of https://feedback.telerik.com/xamarin/1427193-treeview-ios-wrong-visualization-with-custom-itemtemplate

Attached Files:
Duplicated
This item is a duplicate of an already existing item. You can find the original item here:
TreeView: [iOS] Scrolling does not work properly when custom ItemTemplates with different height are used.
5 comments
ADMIN
Didi
Posted on: 17 Oct 2019 14:08

Hello Trevor,

Let me explain in details:

1) prevent items from being selected

Our QA engineers tested the provided project and followed the described steps but they could not reproduce the issue. We have tested with VS 2019 latest version. Could you please update VS, Xcode, Xamarin.iOS SDK, Telerik UI for Xamarin and Xamarin.Forms to their latest versions and check whether the issue could be reproduced. 

2) items causes flickering while scrolling

I haven't said that this behavior is normal, I said: "This is how the native iOS control behaves". - and I explained the reason behind it. Each time the TreeView is scrolled up/down the TreeView cells are redrawn and flickering occurs. This issue is logged and approved in our Feedback portal. You can follow the item here

Regards,
Didi
Progress Telerik

n/a
Posted on: 15 Oct 2019 02:43

Hi Didi,

What else do we need to provide to help you replicate this issue?
In terms of point 2, you mention that this is how the native iOS control behaves.
Just to confirm, you're saying that the TreeView items jumping around randomly during scrolling is normal iOS behaviour?
And as such isn't something that will be fixed?

Thanks 

ADMIN
Didi
Posted on: 07 Oct 2019 11:03

Hi Trevor,

Thank you for the provided video.

Let me get straight to the questions:

1) prevent items from being selected

I have tested the attached project using the latest version of Telerik UI for Xamarin v.2019.3.1004.1 and I could not reproduce the issue. I have tested on iPhoneSimulator 7 with iOS 10.1, 10.3, 11,4, 12.2. and real device with iOS 13 and using Visual Studio 2019. I have attached a video for reference.

2) items randomly change position in the control

This behavior occurs because while scrolling/expanding/collapsing items, the TreeView cells are redrawn and flickering effect occurs while the items are relocated. This is how the native iOS control behaves.

Regards,
Didi
Progress Telerik

Attached Files:
n/a
Posted on: 04 Oct 2019 02:32

Hi Yana 

Attached is a video showing the issue on a physical device running iOS 11.4.1.
We've replicated the issue on iOS versions:
12.1
11.4.1
9.3.5

Both on physical devices and in the iOS Simulator running on a Mac Mini
iOS Simulator - 10.1

The Windows development machine has the following versions installed.
Visual Studio 2017 - 15.9.14
Xamarin - 4.12.3.83
Xamarin.iOS and Xamarin.Mac SDK - 12.4.0.64

Thanks 

Attached Files:
ADMIN
Yana
Posted on: 03 Oct 2019 12:37

Hi Trevor,

Thank you for sending the project. 

Indeed, from the description the issue seems similar. Still, I have difficulties reproducing it on my side - even with the attached project. We also didn't manage to replicate any erroneous behavior after Martin's report.

I would need more details on the setup you have, can you send me the exact VIsual Studio version, iOS version, what iOS simulator you're using?

If you could provide a short video demonstrating the exact issue, that would be of great help as well.

I am looking forward to your reply.

Regards,
Yana
Progress Telerik

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