CFRunLoopAddObserver(_:_:_:)
Adds a CFRunLoopObserver object to a run loop mode.
Declaration
func CFRunLoopAddObserver(_ rl: CFRunLoop!, _ observer: CFRunLoopObserver!, _ mode: CFRunLoopMode!)Parameters
- rl:
The run loop to modify.
- observer:
The run loop observer to add.
- mode:
The run loop mode to which to add
observer. Use the constant Commonmodes to addobserverto the set of objects monitored by all the common modes.
Discussion
A run loop observer can be registered in only one run loop at a time, although it can be added to multiple run loop modes within that run loop.
If rl already contains observer in mode, this function does nothing.