# initializeMemory(as:from:) Initializes the buffer’s memory with the given elements, binding the initialized memory to the elements’ type. ``` func initializeMemory(as type: S.Element.Type, from source: S) -> (unwritten: S.Iterator, initialized: UnsafeMutableBufferPointer) where S : Sequence ``` ## Parameters `type` The type of element to which this buffer’s memory will be bound. `source` A sequence of elements with which to initialize the buffer. ## Return Value An iterator to any elements of `source` that didn’t fit in the buffer, and a typed buffer of the written elements. The returned buffer references memory starting at the same base address as this buffer. ## Discussion When calling the `initializeMemory(as:from:)` method on a buffer `b`, the memory referenced by `b` must be uninitialized or initialized to a trivial type, and must be properly aligned for accessing `S.Element`. The buffer must contain sufficient memory to accommodate `source.underestimatedCount`. This method initializes the buffer with elements from `source` until `source` is exhausted or, if `source` is a sequence but not a collection, the buffer has no more room for source’s elements. After calling `initializeMemory(as:from:)`, the memory referenced by the returned `UnsafeMutableBufferPointer` instance is bound and initialized to type `S.Element`. This method does not change the binding state of the unused portion of `b`, if any. --- 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)