<!--
{
  "availability" : [
    "*: -",
    "iOS: 14.0.0 -",
    "iPadOS: 14.0.0 -",
    "macCatalyst: -",
    "macOS: 11.0.0 -",
    "tvOS: 14.0.0 -",
    "visionOS: -",
    "watchOS: 7.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Accelerate",
  "identifier" : "/documentation/Accelerate/BNNS/PoolingLayer",
  "metadataVersion" : "0.1.0",
  "role" : "Class",
  "symbol" : {
    "kind" : "Class",
    "modules" : [
      "Accelerate"
    ],
    "preciseIdentifier" : "s:10Accelerate4BNNSO12PoolingLayerC"
  },
  "title" : "BNNS.PoolingLayer"
}
-->

# BNNS.PoolingLayer

A layer object that wraps a pooling filter and manages its deinitialization.

```
class PoolingLayer
```

## Topics

### Creating a Pooling Layer

[`convenience init?(type: BNNS.PoolingType, input: BNNSNDArrayDescriptor, output: BNNSNDArrayDescriptor, bias: BNNSNDArrayDescriptor?, activation: BNNS.ActivationFunction, kernelSize: (width: Int, height: Int), stride: (x: Int, y: Int), padding: BNNS.ConvolutionPadding, filterParameters: BNNSFilterParameters?)`](/documentation/Accelerate/BNNS/PoolingLayer/init(type:input:output:bias:activation:kernelSize:stride:padding:filterParameters:))

Returns a new pooling layer.

### Specifying a Pooling Type

[`enum PoolingType`](/documentation/Accelerate/BNNS/PoolingType)

Constants that describe pooling types.

### Applying a Pooling Layer

[`func apply(batchSize: Int, input: BNNSNDArrayDescriptor, output: BNNSNDArrayDescriptor) throws`](/documentation/Accelerate/BNNS/PoolingLayer/apply(batchSize:input:output:))

Applies the layer to a set of input objects, writing the result to a set of output objects.

[`func applyBackward(batchSize: Int, input: BNNSNDArrayDescriptor, output: BNNSNDArrayDescriptor, outputGradient: BNNSNDArrayDescriptor, generatingInputGradient: BNNSNDArrayDescriptor, generatingBiasGradient: BNNSNDArrayDescriptor?) throws`](/documentation/Accelerate/BNNS/PoolingLayer/applyBackward(batchSize:input:output:outputGradient:generatingInputGradient:generatingBiasGradient:))

Applies the layer backward to generate input gradients.

## Relationships

### Inherits From

[`Layer`](/documentation/Accelerate/BNNS/Layer)

---

Copyright &copy; 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)