Question

I’m polling a router from an iPhone. The timer only fires every 60 seconds. I’m starting the timer in ViewDidLoad and leaving it on.

There’s a flag pollingON initially set FALSE.

When the timer fires, it calls myTimerFiredMethod, which then checks,

if (self.pollingON) {
  self.pollingON = FALSE ;
  // run the polling code
  self.pollingON = TRUE ;
}

Aside from wasting a nanosecond or two of CPU time, anything wrong with this practice?

Answer 1

A timer that is running although not in use, is a waste of battery life. It’s also a strange design pattern, running a timer without a cause.

Also if you turn on Polling, at worst you will have to wait almost 60 seconds before an update.

I would not recommend implementing it that way. Instead, invalidate the timer when polling is turned off and create a new timer when polling is turned on.