Prism for Mac

[diamondStar35]

Hello.

I do not know does this fall under an issue or not so I just opened a discussion.

I have tried Prism on Macos 12.6, and here's what I got.

System.DllNotFoundException: Unable to load shared library 'prism' or one of its dependencies. In order to help diagnose loading problems, consider setting the DYLD_PRINT_LIBRARIES environment variable:
dlopen(/Users/nnolan/prism/prism.dylib, 0x0001): tried: '/Users/nnolan/prism/prism.dylib' (no such file)
dlopen(prism.dylib, 0x0001): tried: 'prism.dylib' (no such file), '/usr/local/lib/prism.dylib' (no such file), '/usr/lib/prism.dylib' (no such file), '/Users/nnolan/prism.dylib' (no such file)
dlopen(/Users/nnolan/prism/libprism.dylib, 0x0001): Symbol not found: (_$sSD10FoundationE19_bridgeToObjectiveCSo12NSDictionaryCyF)
Referenced from: '/Users/nnolan/prism/libprism.dylib'
Expected in: '/System/Library/Frameworks/Foundation.framework/Versions/C/Foundation'
dlopen(libprism.dylib, 0x0001): tried: 'libprism.dylib' (no such file), '/usr/local/lib/libprism.dylib' (no such file), '/usr/lib/libprism.dylib' (no such file), '/Users/nnolan/libprism.dylib' (no such file)
dlopen(/Users/nnolan/prism/prism, 0x0001): tried: '/Users/nnolan/prism/prism' (no such file)
dlopen(prism, 0x0001): tried: 'prism' (not a file), '/usr/local/lib/prism' (no such file), '/usr/lib/prism' (no such file), '/Users/nnolan/prism' (not a file)
dlopen(/Users/nnolan/prism/libprism, 0x0001): tried: '/Users/nnolan/prism/libprism' (no such file)
dlopen(libprism, 0x0001): tried: 'libprism' (no such file), '/usr/local/lib/libprism' (no such file), '/usr/lib/libprism' (no such file), '/Users/nnolan/libprism' (no such file)

Because I don't see a minimum requirement for Mac, I decided to first ask before opening an issue since this maybe intended due to min requirements.

Regards.

[ethindp]

This is neither. The library is libprism.dylib/.so on all other platforms but Windows. If it's a static library build, then it's libprism.a.

[diamondStar35]

Excuse me? The log also shows this:

dlopen(/Users/nnolan/prism/libprism.dylib, 0x0001): Symbol not found: (_$sSD10FoundationE19_bridgeToObjectiveCSo12NSDictionaryCyF)

The library is being detected but then the exception is thrown. And no, I'm using the dynamic build.

[ethindp]

My bad. macOS 15 is currently required. That was back when we were using swift so in theory, I could try to lower it again, but I don't know how well that would go and I think python might get very mad at me if I do that.

[diamondStar35]

Many people are still using older versions of Mac, for example Macos 14 or even Macos 12. I understand if Macos 12 would be impossible to support, but at least it should be lowered to the hard minimum version supported.

[ethindp]

@diamondStar35 Apologies for being so abrasive earlier. I accidentally didn't read the entire comment since I was reading through what Discord notifications indicated.

As for lowering the minimum deployment version, definitely worth a try, especially since I need to modify CI workflows to build using CMake's native iOS support and not through the hacky solution I use right now.

[diamondStar35]

@ethindp no problem, everything is fine :)

Thanks for considering this.

[ethindp]

@diamondStar35 Can you please test using the MacOS artifacts for the latest CI run, found here?

[diamondStar35]

@ethindp Sorry, I didn't see the new comment.
Sure, I'll test now.

[diamondStar35]

@ethindp
Luckily this is working on Macos 12. However, Voice Over backend shows that it is not supported at runtime. See this.

Backend probe result:
Id: 0xCB4897961A754BCB
RegistryName: VoiceOver
RegistryPriority: 102
RegistrySupported: True
RuntimeSupported: false
OpenPath: Acquire -> Create failed
Error: AggregateException: One or more errors occurred. (Backend not available) (Backend not available)
End backend probe result.

Timestamp: 2026-05-06 14:46:52.958 -07:00
Backend probe result:
Id: 0x28E3429577805C24
RegistryName: AVSpeech
RuntimeName: AVSpeech
RegistryPriority: 97
RegistrySupported: True
RuntimeSupported: True
OpenPath: Acquire
Parameters:
  Volume: 0.5
  Rate: 0.5
  Pitch: 0.5
  Channels: 1
  SampleRate: 22050
  BitDepth: 32
  CurrentVoiceIndex: 0
  VoiceCount: 50
Features:
  - SupportedAtRuntime: True
  - Speak: True
  - SpeakToMemory: True
  - Braille: False
  - Output: True
  - IsSpeaking: True
  - Stop: True
  - Pause: True
  - Resume: True
  - SetVolume: True
  - GetVolume: True
  - SetRate: True
  - GetRate: True
  - SetPitch: True
  - GetPitch: True
  - RefreshVoices: True
  - CountVoices: True
  - GetVoiceName: True
  - GetVoiceLanguage: True
  - GetVoice: True
  - SetVoice: True
  - GetChannels: True
  - GetSampleRate: True
  - GetBitDepth: True
  - SilenceTrimmingOnSpeak: False
  - SilenceTrimmingOnSpeakToMemory: True
  - SpeakSsml: False
  - SpeakToMemorySsml: False
End backend details.

[ethindp]

This is very odd. On MacOS this probes [[NSWorkspace sharedWorkspace] isVoiceOverEnabled] and on iOS it probes UIAccessibilityIsVoiceOverRunning. In both of these cases, a truthy value is what sets the IS_SUPPORTED_AT_RUNTIME.

[diamondStar35]

Also please note that Prism is unusable on IOS because it is built as a standalone .dylib. Apple documents that standalone .dylib in IOS apps is not supported.

[ethindp]

@diamondStar35 The iOS port is built in both static and dynamic modes. I know that dylib is unsupported by Apple (since they prefer an xcframework or similar), however constructing one would be rather annoying and only packaging the framework would make it harder for language bindings to be created where the language does not support Apple's framework directory structure. So, we leave as it is now to give you maximum flexibility. I am lead to understand that static linking is the typical on iOS, so I don't believe that this will necessarily pose a problem, and you should still be able to use it on iOS. However, if this does cause app store issues I am wide-open to setting up a framework or xcframework if needed.

[diamondStar35]

Thanks for that. Will try static linking then.

[ethindp]

Of course. Did this also solve your original issue?

[diamondStar35]

Of course. Did this also solve your original issue?

Please see the comment where I mentioned that Voice Over backend is showing as unsupported at runtime, while AV speech is working. It did partially solve the issue but I'm confused on why Voice Over is still unavailable though.

The comment is here, you might have missed it: #40 (comment)

[ethindp]

As I said earlier, either [[NSWorkspace sharedWorkspace] isVoiceOverEnabled] or (on iOS UIAccessibilityIsVoiceOverRunning) is returning false. I have no idea why this would be happen -- I'm not doing any other special handling.

[ethindp]

I would need a debugger to analyze the control flow to see where it breaks.

[diamondStar35]

I'm not really sure either. And by the way no that log was from a Mac x64 machine.

Anyway, it resolved the original issue of throwing an exception, so you may want to close it. If I get any new info on why Voice Over is not working, I may open a new discussion in the future but hopefully there will be some kind of a solution.

[ethindp]

Can you provide the code you're using to check the availability? The bug may very well be in your code.

[diamondStar35]

@ethindp
Here is the code I'm using. I don't think the bug comes from my code though feel free to download and build the program.
PrismMacOsX64Repro.zip

[ethindp]

@diamondStar35 So, I really need to make a section describing this in the manual, but the problem is that you don't have an NSApplication main loop or an AppKit window. The VoiceOver backend requires both to be active when it is initialized. If you want it to use the legacy AppleScript method (which allows it to emulate the NVDA controller client or JAWS back-ends with respect to being able to announce things system-wide), you also need Apple Events automation access, which will display a TCC permission prompt. A console / CLI-style program that doesn't start an AppKit run loop is not going to satisfy the VO backend, regardless of whether you launch it from Terminal or from Finder, and in those cases you should fall back to AVSpeech.

This is not a bug in Prism itself but more in its documentation. I appreciate you opening and asking because this is a gap that I do need to close, and I am considering introducing several new error codes to make issues like this much clearer and easier to diagnose, since BackendNotAvailable is becoming a catch-all that we probably don't want.

To fix this, switch to the net9.0-macos TFM (or later), install the macos workload, and change your Program.cs to do something like the following:

using AppKit;
using Foundation;

static class Program
{
    static void Main(string[] args)
    {
        NSApplication.Init();
        NSApplication.SharedApplication.Delegate = new AppDelegate();
        NSApplication.Main(args);
    }
}

sealed class AppDelegate : NSApplicationDelegate
{
    NSWindow? window;

    public override void DidFinishLaunching(NSNotification notification)
    {
        window = new NSWindow(new CoreGraphics.CGRect(0, 0, 1, 1), NSWindowStyle.Borderless, NSBackingStore.Buffered, false);
        window.MakeKeyAndOrderFront(this);
        Task.Run(RunPrismReproAsync);
    }

    async Task RunPrismReproAsync()
    {
        try
        {
            // Initial code runs here
        }
        finally
        {
            NSApplication.SharedApplication.InvokeOnMainThread(() => NSApplication.SharedApplication.Terminate(this));
        }
    }
}

I could be slightly off here (I have little experience with MacOS apps in .NET) but this is the general pattern. When integrating this into actual GUI apps, most of this boilerplate should be handled by whatever toolkit or game framework you're using.

[diamondStar35]

@ethindp
I'm so sorry for being too late following this discussion. I appreciate your response.

You can consider this as closed since you answered me with the solution. Hopefully will see something in the manual about this so people will be aware of it.

Thanks so much!