# init(toBuffer:capacity:) Returns an initialized output stream that can write to a provided buffer. ``` init(toBuffer buffer: UnsafeMutablePointer, capacity: Int) ``` ## Parameters `buffer` The buffer the output stream will write to. `capacity` The size of the buffer in bytes. ## Return Value An initialized output stream that can write to `buffer`. ## Discussion The stream must be opened before it can be used. When the number of bytes written to `buffer` has reached `capacity`, the stream’s [`streamStatus`](/documentation/Foundation/Stream/streamStatus) will return `NSStreamStatusAtEnd`. ## See Also [`outputStreamToBuffer:capacity:`](/documentation/Foundation/NSOutputStream/outputStreamToBuffer:capacity:) Creates and returns an initialized output stream that can write to a provided buffer. --- 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)