我有这个代码块:
DispatchQueue.main.asyncAfter(deadline: .now() + (delay * Double(isDelayAccounted.hashValue)) + extraDelay) {
self.isShootingOnHold = false
self.shoot()
self.shootingEngine = Timer.scheduledTimer(timeInterval: (Double(60)/Double(self.ratePerMinute)), target: self, selector: #selector(ShootingEnemy.shoot), userInfo: nil, repeats: true)
}
现在,我希望能够阻止此线程执行。如何阻止它被执行?例如,3 秒后,我决定不再执行它,所以我想停止它。
您可以使用
DispatchWorkItem
s。它们可以安排在 DispatchQueue
上,并在执行前取消。
let work = DispatchWorkItem(block: {
self.isShootingOnHold = false
self.shoot()
self.shootingEngine = Timer.scheduledTimer(timeInterval: (Double(60)/Double(self.ratePerMinute)), target: self, selector: #selector(ShootingEnemy.shoot), userInfo: nil, repeats: true)
})
DispatchQueue.main.asyncAfter(deadline: .now() + (delay * Double(isDelayAccounted.hashValue)) + extraDelay, execute: work)
work.cancel()
您可以使用
一次性DispatchSourceTimer
而不是asyncAfter
var oneShot : DispatchSourceTimer!
oneShot = DispatchSource.makeTimerSource(queue: DispatchQueue.main)
oneShot.scheduleOneshot(deadline: .now() + (delay * Double(isDelayAccounted.hashValue)) + extraDelay))
oneShot.setEventHandler {
self.isShootingOnHold = false
self.shoot()
self.shootingEngine = Timer.scheduledTimer(timeInterval: (Double(60)/Double(self.ratePerMinute)), target: self, selector: #selector(ShootingEnemy.shoot), userInfo: nil, repeats: true)
}
oneShot.setCancelHandler {
// do something after cancellation
}
oneShot.resume()
并取消执行
oneShot?.cancel()
oneShot = nil