# CFStreamCreatePairWithSocketToNetService(_:_:_:_:) Creates a pair of streams for a CFNetService. ``` func CFStreamCreatePairWithSocketToNetService(_ alloc: CFAllocator?, _ service: CFNetService, _ readStream: UnsafeMutablePointer?>?, _ writeStream: UnsafeMutablePointer?>?) ``` ## Parameters `alloc` The allocator to use to allocate memory for the `CFReadStream` and `CFWriteStream` objects. Pass `NULL` or kCFAllocatorDefault to use the current default allocator. `service` Reference to the `CFNetService` to which the streams are to be connected. If the service is not resolved, the service will be resolved before the streams are connected. `writeStream` Upon return, contains a `CFWriteStream` object connected to the service specified by `service`, or `NULL` if there is a failure during creation. If you pass `NULL`, the function will not create a writable stream. Ownership follows the [The Create Rule](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029). ## Discussion The streams do not create a socket, resolve the service, or connect to the service’s host until you open one of the streams. Most properties are shared by both streams. Setting a shared property for one stream automatically sets the property for the other. ### Special Considerations This function is thread safe. --- 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)