# withUnsafeMutableShapedBufferPointer(using:_:) Calls the given closure with a pointer to the array’s mutable storage that has a specified buffer layout. ``` mutating func withUnsafeMutableShapedBufferPointer(using bufferLayout: MLShapedArrayBufferLayout, _ body: (inout UnsafeMutableBufferPointer, [Int], [Int]) throws -> R) rethrows -> R ``` ## Discussion The storage contains the scalars according to buffer layout parameter. For example, the scalar at `[x1, x2, ... xn]` with strides `[s1, s2, ... sn]` is stored at `ptr[x1 * s1 + x2 * s2 + ... + xn * sn]` Unlike `withUnsafeMutableShapedBufferPointer(:)`, this function allows the caller to specify the buffer layout. ```swift // Initialize the middle 2x2 of 4x4 shaped array using an external data that lays out // scalars in last-major order. let data: [Int32] = [1, 3, 2, 4] var array = MLShapedArray(repeating: 0, shape: [4, 4]) array[1...2, 1...2].withUnsafeMutableShapedBufferPointer(using: .lastMajorContiguous) { destinationPtr, _, _ in data.withUnsafeBufferPointer() { sourcePtr in destinationPtr.update(from: sourcePtr) } } // array.scalars == [0, 0, 0, 0, // 0, 1, 2, 0, // 0, 3, 4, 0, // 0, 0, 0, 0,]) ``` --- 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)