[iOS] BlazorWebView components not rendering on .NET 10 - Blazor starts but RootComponent is not injected into DOM

[spanglerp]

Description

BlazorWebView on iOS (.NET 10) starts Blazor successfully, but the RootComponent is never rendered into the DOM. The #app element remains unchanged. This works correctly on Android with the same codebase.

Steps to Reproduce

1. Create a .NET 10 MAUI Blazor Hybrid app
2. Build for iOS with dotnet publish -f net10.0-ios -c Release
3. Install and run on iOS device
4. Observe that Blazor starts (confirmed via JavaScript: Blazor.start() throws "Blazor has already started")
5. But the RootComponent is never rendered - the #app div stays empty

Expected Behavior

The Blazor component registered in MainPage.xaml should render into the #app element.

Actual Behavior

• HTML loads correctly ✓
• JavaScript executes ✓
• blazor.webview.js loads ✓
• Blazor starts automatically ✓
• But RootComponent is NOT rendered ✗

The #app div remains unchanged. Even a minimal component with just <h1>Test</h1> (no code) does not render.

Environment

• .NET SDK: 10.0.100
• Microsoft.Maui.Controls: 10.0.10
• Microsoft.AspNetCore.Components.WebView.Maui: 10.0.10
• Target: iOS 17.0+
• Device: iPhone (physical device)
• Build: Release with AOT

Workarounds Attempted (all failed)

• Disabled AOT (PublishAot=false, UseInterpreter=true)
• Disabled trimming (MtouchLink=None) - app crashes
• Added TrimmerRootAssembly for Maui assembly
• Programmatically added RootComponent in code-behind
• Simplified component to just HTML (no @code block)
• Removed all external CSS/JS references

Additional Context

The same app works on Android. The issue appears to be iOS-specific in .NET 10.

Build output shows many trim warnings related to Blazor components:

Trim analysis warning IL2111: Method 'Microsoft.AspNetCore.Components.Routing.Router.NotFoundPage.set' with parameters or return value with DynamicallyAccessedMembersAttribute is accessed via reflection.

Link to public reproduction project repository

https://github.com/spanglerp/maui-blazor-ios-bug

Version with bug

10.0.10

Is this a regression from previous behavior?

No, this is something new

Last version that worked well

10.0.10

Affected platforms

iOS

Affected platform versions

IOS 26

Did you find any workaround?

No response

Relevant log output

[sheiksyedm]

This issue did not reproduce on the iOS simulator, so it appears to occur only on a physical iOS device.

[spanglerp]

@sheiksyedm Thanks for this important info!

Yes, we tested on a physical iPhone only. This makes sense because:

• iOS Simulator runs on x64/ARM Mac and uses JIT compilation
• Physical iOS devices require AOT (Ahead-of-Time) compilation due to Apple's restrictions

The bug is likely related to how Blazor components are registered/resolved during AOT compilation. The trimmer/AOT compiler might be stripping something that's needed for the BlazorWebView to inject the RootComponent.

[spanglerp]

Small addition and a possible Workaround is to Build the IOS ipa without AOT with -p:iOSNoAot=1. This confirmes the Problem has something to do with the AOT.

NOTE: you can't Puslish your App in this case to IOS Appstore because AOT is required.

[aastovas]

Hello, dumb question, but -p:iOSNoAot=1translates to PublishAot false in the csproj file? I have been struggling to make iOS build work in testflight using lots of combinations RunAOTCompilation, PublishAot, PublishAotUsingRuntimePack, MtouchLink (which btw takes makes compilation take ages when set to None) etc, but blazor part just doesn't render, starting to lose hope :)

UPDATE: with latest version 10.0.40, I have been able to publish on iOS without any compilation tweaks. The only thing I have changed is to put Routes.razor and _Imports.razor at the root of the project.