[Mobile] CoreML Execution Provider not listed in supported values

[hpx2939]

Describe the issue

Hi,

I’m trying to add the CoreML Execution Provider with custom options:

std::unordered_map<std::string, std::string> provider_options;
provider_options["ModelFormat"] = "MLProgram";         
provider_options["MLComputeUnits"] = "ALL";           
provider_options["RequireStaticShapes"] = "0";          
provider_options["EnableSubgraphs"] = "0";            

session_options.AppendExecutionProvider("CoreML", provider_options);

But I got an error saying:

Currently supported values are 'OPENVINO', 'SNPE', 'XNNPACK', 'QNN', 'WEBNN' and 'AZURE'

Questions:
Is CoreML EP still supported in the latest version of ONNX Runtime?
If yes, what is the correct way to enable it (and what string should I use in AppendExecutionProvider)?
Are the provider options I’m using still valid for CoreML EP?

Thanks!

To reproduce

1. Build ONNX Runtime for iOS using CoreML support (or use the latest prebuilt version).
2. Create a Ort::SessionOptions object.
3. Call AppendExecutionProvider("CoreML", provider_options) with the options above.
4. Observe the error about unsupported execution provider.

Urgency

No response

Platform

iOS

OS Version

18.3.1

ONNX Runtime Installation

Built from Source

Compiler Version (if 'Built from Source')

No response

Package Name (if 'Released Package')

None

ONNX Runtime Version or Commit ID

1.20.0

ONNX Runtime API

C++/C

Architecture

ARM64

Execution Provider

CoreML

Execution Provider Library Version

No response

[edgchen1]

In 1.20, it looks like adding the CoreML EP wasn't supported with Ort::SessionOptions::AppendExecutionProvider() yet.

That should work starting from 1.21:

onnxruntime/onnxruntime/core/session/provider_registration.cc

Lines 163 to 165 in e0b66ca

	} else if (strcmp(provider_name, "CoreML") == 0) {
	#if defined(USE_COREML)
	options->provider_factories.push_back(CoreMLProviderFactoryCreator::Create(provider_options));

In older versions, you can use the old way of adding it, OrtSessionOptionsAppendExecutionProvider_CoreML():

onnxruntime/include/onnxruntime/core/providers/coreml/coreml_provider_factory.h

Lines 85 to 86 in 47f355a

	ORT_EXPORT ORT_API_STATUS(OrtSessionOptionsAppendExecutionProvider_CoreML,
	_In_ OrtSessionOptions* options, uint32_t coreml_flags);

[hpx2939]

Hi @edgchen1,

I built ONNX Runtime 1.21.0 for iOS with --use_coreml and created a static libonnxruntime_complete.a and corresponding XCFramework. My build steps:

./build.sh --config Release \
  --use_xcode \
  --ios \
  --apple_sysroot iphoneos \
  --osx_arch arm64 \
  --apple_deploy_target 16.0 \
  --use_coreml \
  --parallel

libtool -static -o libonnxruntime_complete.a \
  libonnxruntime_session.a \
  libonnxruntime_framework.a \
  libonnxruntime_providers_coreml.a \
  libonnxruntime_providers.a \
  libonnxruntime_graph.a \
  libonnxruntime_optimizer.a \
  libonnxruntime_common.a \
  libonnxruntime_util.a \
  libonnxruntime_mlas.a \
  libonnxruntime_flatbuffers.a \
  libonnxruntime_lora.a

xcodebuild -create-xcframework \
  -library build/iOS/Release/Release-iphoneos/libonnxruntime_complete.a \
  -headers headers_complete \
  -output onnxruntime.xcframework

Then I integrated the XCFramework into my Xcode project.

In my app, I call the new API:

so.AppendExecutionProvider("CoreML", provider_options);

…but on a real device (iPhone 16 Pro), I still get:

Unknown provider name. Currently supported values are 'OPENVINO', 'SNPE', 'XNNPACK', 'QNN', 'WEBNN' and 'AZURE'

Do I need to use the old API OrtSessionOptionsAppendExecutionProvider_CoreML() even in 1.21.0 for real devices? Or is there some additional build/config step to enable CoreML EP on actual iPhones?

Available EPs:
  - CoreMLExecutionProvider
  - XnnpackExecutionProvider
  - CPUExecutionProvider

ORT API Version: 21

Thanks!

[edgchen1]

Unknown provider name. Currently supported values are 'OPENVINO', 'SNPE', 'XNNPACK', 'QNN', 'WEBNN' and 'AZURE'

This error message doesn't look like what should be appearing in 1.21:
https://github.com/microsoft/onnxruntime/blob/v1.21.0/onnxruntime/core/session/provider_registration.cc#L171-L172

I'd double check the version being run.

Do I need to use the old API OrtSessionOptionsAppendExecutionProvider_CoreML() even in 1.21.0 for real devices? Or is there some additional build/config step to enable CoreML EP on actual iPhones?

The old API should work, but I'd expect the new one to work too in 1.21. There shouldn't be any additional steps required for running on real devices.