Creates a CFRunLoopObserver object with a function callback.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
- Core Foundation
The allocator to use to allocate memory for the new object. Pass
kto use the current default allocator.
A flag identifying whether the observer should be called only once or every time through the run loop. If
false, the observer is invalidated after it is called once, even if the observer was scheduled to be called at multiple stages within the run loop.
A priority index indicating the order in which run loop observers are processed. When multiple run loop observers are scheduled in the same activity stage in a given run loop mode, the observers are processed in increasing order of this parameter. Pass 0 unless there is a reason to do otherwise.
The callback function invoked when the observer runs.
A structure holding contextual information for the run loop observer. The function copies the information out of the structure, so the memory pointed to by
contextdoes not need to persist beyond the function call. Can be
NULLif the observer does not need the context’s
infopointer to keep track of state.
The new CFRunLoopObserver object. Ownership follows the Create Rule described in Ownership Policy.
The run loop observer is not automatically added to a run loop. To add the observer to a run loop, use
CFRun. An observer can be registered to only one run loop, although it can be added to multiple run loop modes within that run loop.