Schedules a repeating timer with the specified time, repeat interval, and leeway values.
- iOS 8.0–11.0Deprecated
- macOS 10.10–10.13Deprecated
- tvOS 9.0–11.0Deprecated
- watchOS 2.0–4.0Deprecated
- Xcode 8.0–9.0Deprecated
The time at which to execute the dispatch source's event handler.
The repeat interval for the timer, measured in seconds.
The maximum amount of time after
wallby which the system may delay the delivery of the timer event.
The system may defer the deliver of timer events to improve power consumption and system performance. The first time the timer fires, the maximum allowable delay is equal to the value in the
leeway parameter. For subsequent firings, the timer fires at
wall, and the maximum delay is equal to
min(leeway, repeating/2)—that is, the smaller of either the
leeway value or half the value in the
The system may fire a timer sooner than the value in the
wall parameter. If you created the timer with the
strict flag, the system makes every effort to observe the provided
leeway value, even if it is smaller than the current lower limit.
Calling this method on a cancelled dispatch source has no effect.