private var timer: dispatch_source_t? = nil
private func startTimer() {
let updateInterval: UInt64 = 1
let interval = updateInterval * NSEC_PER_SEC
let leeway: UInt64 = 300000000 // UInt64(0.3) * interval
let queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue)
if timer != nil {
dispatch_source_set_timer(timer!, dispatch_walltime(nil, 0), interval, leeway)
dispatch_source_set_event_handler(timer!, { () -> Void in
self.checkNewScreenshot()
})
}
dispatch_resume(timer!)
}
private func stopTimer() {
if timer != nil {
dispatch_suspend(timer!)
dispatch_resume(timer!)
timer = nil
}
}