.NET 8 iOS binding to NSString returns null

[akravch]

Steps to Reproduce

1. Get a static .a library that has an NSString field in code: NSString *Foo = @"Bar";.

2. Create an iOS binding project that binds to the static lib and to the field:

    [Static]
    interface Constants
    {
        // extern NSString * Foo;
        [Field("Foo", "__Internal")]
        NSString Foo { get; }
    }

3. Create a .NET 8 iOS project that would reference the binding project.

4. Log Constants.Foo.

Expected Behavior

Constants.Foo returns "Bar".

Actual Behavior

Constants.Foo returns null.

If we change the target framework of the consumer project from .NET 8 to .NET 7, "Bar" is returned as expected. Also, from what I can see, it doesn't matter if the binding project is .NET 7 or .NET 8.

Environment

.NET 8.0.101
iOS workload 17.2.8004/8.0.100
XCode 15.2
iOS Simulator with iOS 17.2
macOS Sonoma 14.3
Apple Silicon M1

Build Logs

log.binlog.zip

Example Project

https://github.com/akravch/IosNet8Binding

I bind to https://github.com/microsoft/plcrashreporter/releases/tag/1.11.1 and log PLCrashReporterException field.

I chose the PLCrashReporter library simply because it was the first thing that came to my mind I could find already compiled, but the behavior is the same regardless of the library.

[rolfbjarne]

I can reproduce this.

As a workaround you can add this to your consuming csproj:

<PropertyGroup>
    <_ExportSymbolsExplicitly>false</_ExportSymbolsExplicitly>
</PropertyGroup>

[akravch]

I can reproduce this.

As a workaround you can add this to your consuming csproj:

<PropertyGroup>
    <_ExportSymbolsExplicitly>false</_ExportSymbolsExplicitly>
</PropertyGroup>

Apparently it only helps with the simulator build. When I deploy the app the a real device, those fields remain null. It may be a different issue though, because in this case switching to .NET 7 doesn't help either.

Any thoughts on a workarounds that would work for a device?

[rolfbjarne]

Try adding the following to your csproj:

<PropertyGroup>
    <_ExportSymbolsExplicitly>false</_ExportSymbolsExplicitly>
    <NoSymbolStrip>true</NoSymbolStrip>
</PropertyGroup>
<ItemGroup>
    <_MainLinkerFlags Include="-u" />
    <_MainLinkerFlags Include="_PLCrashReporterException" />
</ItemGroup>