Created
November 12, 2019 16:28
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Using Core ML with Combine
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import CoreML | |
import Combine | |
extension Publisher where Self.Output: MLFeatureProvider { | |
/** | |
Operator that lets you run a Core ML model as part of a Combine chain. | |
It accepts an MLFeatureProvider object as input, and, if all goes well, | |
returns another MLFeatureProvider with the model outputs. | |
Since Core ML can give errors, we put everything in a Result object. | |
Use the `compactMap` version to always ignore errors, or `tryMap` to | |
complete the subscription upon the first error. | |
To perform the Core ML request on a background thread, it's probably a good | |
idea to write a custom Publisher class, but for simple use cases `map` works | |
well enough. | |
*/ | |
public func prediction(model: MLModel) -> Publishers.Map<Self, Result<MLFeatureProvider, Error>> { | |
map { input in | |
do { | |
return .success(try model.prediction(from: input)) | |
} catch { | |
return .failure(error) | |
} | |
} | |
} | |
public func prediction(model: MLModel) -> Publishers.CompactMap<Self, MLFeatureProvider> { | |
compactMap { input in try? model.prediction(from: input) } | |
} | |
public func prediction(model: MLModel) -> Publishers.TryMap<Self, MLFeatureProvider?> { | |
tryMap { input in try model.prediction(from: input) } | |
} | |
} |
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