# CFRunLoopTimerCreate(_:_:_:_:_:_:_:) Creates a new CFRunLoopTimer object with a function callback. ``` func CFRunLoopTimerCreate(_ allocator: CFAllocator!, _ fireDate: CFAbsoluteTime, _ interval: CFTimeInterval, _ flags: CFOptionFlags, _ order: CFIndex, _ callout: CFRunLoopTimerCallBack!, _ context: UnsafeMutablePointer!) -> CFRunLoopTimer! ``` ## Parameters `allocator` The allocator to use to allocate memory for the new object. Pass `NULL` or [`kCFAllocatorDefault`](/documentation/CoreFoundation/kCFAllocatorDefault) to use the current default allocator. `fireDate` The time at which the timer should first fire. The fine precision (sub-millisecond at most) of the fire date may be adjusted slightly by the timer if there are implementation reasons to do so. `interval` The firing interval of the timer. If `0` or negative, the timer fires once and then is automatically invalidated. The fine precision (sub-millisecond at most) of the interval may be adjusted slightly by the timer if implementation reasons to do so exist. `flags` Currently ignored. Pass `0` for future compatibility. `order` A priority index indicating the order in which run loop timers are processed. Run loop timers currently ignore this parameter. Pass `0`. `callout` The callback function that is called when the timer fires. `context` A structure holding contextual information for the run loop timer. The function copies the information out of the structure, so the memory pointed to by `context` does not need to persist beyond the function call. Can be `NULL` if the callback function does not need the context’s `info` pointer to keep track of state. ## Return Value The new CFRunLoopTimer object. 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 A timer needs to be added to a run loop mode before it will fire. To add the timer to a run loop, use [`CFRunLoopAddTimer(_:_:_:)`](/documentation/CoreFoundation/CFRunLoopAddTimer(_:_:_:)). A timer can be registered to only one run loop at a time, although it can be in multiple modes within that run loop. --- 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)