# MIDIClientCreate(_:_:_:_:) Creates a MIDI client. ``` func MIDIClientCreate(_ name: CFString, _ notifyProc: MIDINotifyProc?, _ notifyRefCon: UnsafeMutableRawPointer?, _ outClient: UnsafeMutablePointer) -> OSStatus ``` ## Parameters `name` The client’s name. `notifyProc` An optional callback function through which the client receives notifications of changes to the system. `notifyRefCon` A void pointer. `outClient` On successful return, points to the newly created MIDI client. ## Return Value An `OSStatus` result code. ## Discussion The system invokes the callback function on the same run loop that you created the client on. ## Topics ### Callbacks [`MIDINotifyProc`](/documentation/CoreMIDI/MIDINotifyProc) A callback function for notifying clients of state changes. [`MIDINotification`](/documentation/CoreMIDI/MIDINotification) A message that describes a system state change. --- 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)