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xamarin / xamarin-macios

.NET for iOS, Mac Catalyst, macOS, and tvOS provide open-source bindings of the Apple SDKs for use with .NET managed languages such as C#
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MaterialComponents.MultilineTextField.TextView.Delegate gets set to null and breaks EventHandlers #7235

Open PureWeen opened 5 years ago

PureWeen commented 5 years ago

Steps to Reproduce

  1. Download sample
  2. Deploy to physical device (I've been using an iPad with iOS 13)
  3. Anything you type inside the entry field should output to the debug window.
  4. If you hit the enter key enough times you'll notice at some point it stops outputing anything
  5. in the iOS project locate CustomEditorRenderer
  6. If you uncomment this line // _localDelegateSave = TextView.Delegate;
  7. Now rerun the project
  8. Now no matter what you type or how many times you hit enter the delegate isn't lost

Here's the fix we are applying to Xamarin.Forms https://github.com/xamarin/Xamarin.Forms/pull/8011/files#diff-71148fd2814c3d17185db42cc58913ffR173

Here's the issue people are having https://github.com/xamarin/Xamarin.Forms/issues/5500

Expected Behavior

I shouldn't have to save the TextView.Delegate to a local variable

Actual Behavior

I have to save it to a local variable otherwise it gets set to null on the TextView

Environment

Microsoft Visual Studio Enterprise 2019
Version 16.3.4
VisualStudio.16.Release/16.3.4+29409.12
Microsoft .NET Framework
Version 4.8.03752

Installed Version: Enterprise

Visual C++ 2019   00435-60000-00000-AA022
Microsoft Visual C++ 2019

Application Insights Tools for Visual Studio Package   9.1.00913.1
Application Insights Tools for Visual Studio

ASP.NET and Web Tools 2019   16.3.285.24939
ASP.NET and Web Tools 2019

ASP.NET Web Frameworks and Tools 2019   16.3.285.24939
For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0   16.3.285.24939
Azure App Service Tools v3.0.0

Azure Functions and Web Jobs Tools   16.3.285.24939
Azure Functions and Web Jobs Tools

C# Tools   3.3.1-beta3-19461-02+2fd12c210e22f7d6245805c60340f6a34af6875b
C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Common Azure Tools   1.10
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Extensibility Message Bus   1.2.0 (d16-2@8b56e20)
Provides common messaging-based MEF services for loosely coupled Visual Studio extension components communication and integration.

IntelliCode Extension   1.0
IntelliCode Visual Studio Extension Detailed Info

Markdown Editor   1.12.236
A full featured Markdown editor with live preview and syntax highlighting. Supports GitHub flavored Markdown.

Microsoft Azure Tools   2.9
Microsoft Azure Tools for Microsoft Visual Studio 0x10 - v2.9.20816.1

Microsoft Continuous Delivery Tools for Visual Studio   0.4
Simplifying the configuration of Azure DevOps pipelines from within the Visual Studio IDE.

Microsoft JVM Debugger   1.0
Provides support for connecting the Visual Studio debugger to JDWP compatible Java Virtual Machines

Microsoft Library Manager   2.0.83+gbc8a4b23ec
Install client-side libraries easily to any web project

Microsoft MI-Based Debugger   1.0
Provides support for connecting Visual Studio to MI compatible debuggers

Microsoft Visual C++ Wizards   1.0
Microsoft Visual C++ Wizards

Microsoft Visual Studio Tools for Containers   1.1
Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.

Microsoft Visual Studio VC Package   1.0
Microsoft Visual Studio VC Package

Mono Debugging for Visual Studio   16.3.7 (9d260c5)
Support for debugging Mono processes with Visual Studio.

NuGet Package Manager   5.3.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit https://docs.nuget.org/

Project System Tools   1.0
Tools for working with C#, VisualBasic, and F# projects.

ProjectServicesPackage Extension   1.0
ProjectServicesPackage Visual Studio Extension Detailed Info

Snapshot Debugging Extension   1.0
Snapshot Debugging Visual Studio Extension Detailed Info

SQL Server Data Tools   16.0.61908.27190
Microsoft SQL Server Data Tools

Test Adapter for Boost.Test   1.0
Enables Visual Studio's testing tools with unit tests written for Boost.Test.  The use terms and Third Party Notices are available in the extension installation directory.

Test Adapter for Google Test   1.0
Enables Visual Studio's testing tools with unit tests written for Google Test.  The use terms and Third Party Notices are available in the extension installation directory.

TypeScript Tools   16.0.10821.2002
TypeScript Tools for Microsoft Visual Studio

Visual Basic Tools   3.3.1-beta3-19461-02+2fd12c210e22f7d6245805c60340f6a34af6875b
Visual Basic components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Visual F# Tools 10.4 for F# 4.6   16.3.0-beta.19455.1+0422ff293bb2cc722fe5021b85ef50378a9af823
Microsoft Visual F# Tools 10.4 for F# 4.6

Visual Studio Code Debug Adapter Host Package   1.0
Interop layer for hosting Visual Studio Code debug adapters in Visual Studio

Visual Studio Tools for CMake   1.0
Visual Studio Tools for CMake

Visual Studio Tools for CMake   1.0
Visual Studio Tools for CMake

Visual Studio Tools for Containers   1.0
Visual Studio Tools for Containers

VisualStudio.Mac   1.0
Mac Extension for Visual Studio

Xamarin   16.3.0.277 (d16-3@c0fcab7)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin Designer   16.3.0.246 (remotes/origin/d16-3@bd2f86892)
Visual Studio extension to enable Xamarin Designer tools in Visual Studio.

Xamarin Templates   16.3.565 (27e9746)
Templates for building iOS, Android, and Windows apps with Xamarin and Xamarin.Forms.

Xamarin.Android SDK   10.0.3.0 (d16-3/4d45b41)
Xamarin.Android Reference Assemblies and MSBuild support.
    Mono: mono/mono/2019-06@5608fe0abb3
    Java.Interop: xamarin/java.interop/d16-3@5836f58
    LibZipSharp: grendello/LibZipSharp/d16-3@71f4a94
    LibZip: nih-at/libzip/rel-1-5-1@b95cf3fd
    ProGuard: xamarin/proguard/master@905836d
    SQLite: xamarin/sqlite/3.27.1@8212a2d
    Xamarin.Android Tools: xamarin/xamarin-android-tools/d16-3@cb41333

Xamarin.iOS and Xamarin.Mac SDK   13.4.0.2 (e37549b)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

Build Logs

BuildLog.txt

Example Project (If Possible)

VanishingDelegate.zip

rolfbjarne commented 5 years ago

The problem is that the TextView instance is collected by the GC (which means TextView's Dispose method is called, which nulls out the Delegate field, which makes everything visibly break).

I have not yet figured out why the TextView instance is collected.

PureWeen commented 5 years ago

We've had to account for these kinds of things a few places

Most recently https://github.com/xamarin/Xamarin.Forms/blob/master/Xamarin.Forms.Platform.iOS/Renderers/PageRenderer.cs#L20

Which we instantiate inside LoadView

https://github.com/xamarin/Xamarin.Forms/blob/master/Xamarin.Forms.Platform.iOS/Renderers/PageRenderer.cs#L155

If we didn't store the view locally then it was getting disposed of.
Especially when using the designer.