# scoped(to:) Creates a copy of a parameter key and adds the scope to it. ``` func scoped(to scope: String) -> MLParameterKey ``` ## Parameters `scope` A scope that targets the key to an internal component of a model. ## Return Value A new parameter key. ## Discussion Use this method to target: - A specific layer of a model - A specific model within a pipeline model - A specific layer of a model within a pipeline model For example, to target an [`MLParameterKey`](/documentation/CoreML/MLParameterKey) to a layer in a model, scope the key with the layer’s name. ```swift let weightsKey = MLParameterKey.weights // Weights key scoped to the "FullyConnected" layer within a model. let fullyConnectedWeights = weightsKey.scoped(to: "FullyConnected") // Prints "Key 1: FullyConnected.weights". print("Key 1: \(fullyConnectedWeights)") ``` To target a model within a pipeline model, scope the [`MLParameterKey`](/documentation/CoreML/MLParameterKey) with the model’s name. ```swift // Number-of-neighbors key scoped to the first model in a pipeline model. let firstModelNumberOfNeighbors = MLParameterKey.numberOfNeighbors.scoped(to: "model0") // Prints "Key 2: model0.numberOfNeighbors". print("Key 2: \(firstModelNumberOfNeighbors)") ``` To target a layer of a model within a pipeline model, start with an [`MLParameterKey`](/documentation/CoreML/MLParameterKey) you’ve already scoped to the model, and add an additional scope with the layer’s name. ```swift let model1Biases = MLParameterKey.biases.scoped(to: "model1") // Biases key scoped to the "FullyConnected" layer of the second model in a pipeline model. let secondModelFullyConnectedBiases = model1Biases.scoped(to: "FullyConnected") // Prints "Key 3: model1.FullyConnected.biases". print("Key 3: \(secondModelFullyConnectedBiases)") ``` By default, a pipeline model names its individual models in the pipeline as `model0`, `model1`, and so on. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)