Could not create inference context

Question

While trying to learn about coreML, I ran into an issue. Using a model from Apple's website (MobileNetV2) I had no issues. When I tried to use my own model that I created, I ran into the issue and the localized description was "Could not create inference context" when using the iPhone simulator. After a quick search I tested this using the arm64 simulator and it worked just fine. I believe this is an m1 related bug because another forum said it worked without any issues on intel Mac, but not their m1.


        if let data = self.animal.imageData {

            do {

                let modelFile = try! DogorCatmodel1(configuration: MLModelConfiguration())

                let model = try VNCoreMLModel(for: modelFile.model)

                

                let handler = VNImageRequestHandler(data: data)

                

                let request = VNCoreMLRequest(model: model) { (request, error) in

                    guard let results = request.results as? [VNClassificationObservation] else {

                        print("Could not classify")

                        return

                    }

                    

                    for classification in results {

                        var identifier = classification.identifier

                        identifier = identifier.prefix(1).capitalized + identifier.dropFirst()

                        print(identifier)

                        print(classification.confidence)

                    }

                }

                

                do {

                    try handler.perform([request])

                }

                catch {

                    print(error.localizedDescription)

                    print("Invalid")

                }

            }

            catch {

                print(error.localizedDescription)

            }

        }

    }

666

Posted by

elichartnett

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Answer 1

Hello! Default model configuration (MLModelConfiguration()) tries to run the model on CPU, GPU and NeuralEngine. NeuralEngine is not supported in the Simulator, which could explain the issue. Could you please file a bug report with the model and some sample code on http://feedbackassistant.apple.com/

Posted by

Frameworks Engineer

Thank you for the response! That is good insight, but I was also trying to use the default model configuration for MobileNetV2 model and had no issues in the simulator. The issue was only with the model I trained. My model would work using the arm64 simulator or when I installed on my physical iPhone, just not in the iOS simulator.

—
elichartnett

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Answer 2

I'm seeing this error for Apple’s own Vision/Image models in tvOS Simulator using Xcode 13.2.1 and tvOS 15.2 on an M1 Max.

Here is the code snippet that causes the error:

	let requestHandler = VNImageRequestHandler(cgImage: cgImage)

	let objectness = VNGenerateObjectnessBasedSaliencyImageRequest()

	let attention = VNGenerateAttentionBasedSaliencyImageRequest()

	let faces = VNDetectFaceRectanglesRequest()



	do {

		try requestHandler.perform([objectness, attention, faces])

	} catch {

		print("Error analyzing image: \(error)")

		return nil

	}

And as a workaround based on the above response from Apple, this works:

	let requestHandler = VNImageRequestHandler(cgImage: cgImage)

	let objectness = VNGenerateObjectnessBasedSaliencyImageRequest()

	let attention = VNGenerateAttentionBasedSaliencyImageRequest()

	let faces = VNDetectFaceRectanglesRequest()


	#if targetEnvironment(simulator)

	objectness.usesCPUOnly = true

	attention.usesCPUOnly = true

	faces.usesCPUOnly = true

	#endif

	do {

		try requestHandler.perform([objectness, attention, faces])

	} catch {

		print("Error analyzing image: \(error)")

		return nil

	}

Posted by

shaun

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Answer 3

Setting request.usesCPUOnly = true solved the issue for me on an M1 Max, Xcode 13.2.1

Posted by

levisz

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Could not create inference context

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