ios - make my enemy spawn a little faster when reach a certain score -

func updatetimer() {     if score < 10 {         runaction(skaction.repeatactionforever(skaction.sequence([skaction.runblock(addenemy), skaction.waitforduration(1.0)])))     }else if score == 10 {         runaction(skaction.repeatactionforever(skaction.sequence([skaction.runblock(addenemy), skaction.waitforduration(0.5)])))     }else if score == 20 {         runaction(skaction.repeatactionforever(skaction.sequence([skaction.runblock(addenemy), skaction.waitforduration(0.1)])))     } } 

i trying make spawn faster when player reach score code has error can me please thank whoever answers question

i wanted make 1

func updatetimer() {     if score < 3 {     timerdots = nstimer.scheduledtimerwithtimeinterval(1.5, target: self, selector: "firedot", userinfo: nil, repeats: true)      // dots generated bit faster before after score reaches 3     } else if score == 3 {         timerdots?.invalidate()         timerdots = nstimer.scheduledtimerwithtimeinterval(1.0, target: self, selector: "firedot", userinfo: nil, repeats: true)      // dots generated faster before after score reaches 12     } else if score == 12 {         timerdots?.invalidate()         timerdots = nstimer.scheduledtimerwithtimeinterval(0.9, target: self, selector: "firedot", userinfo: nil, repeats: true)     }  } 

it's simpler using instance variable , skscene update: method:

private var score: int = 0 private var priorenemyaddtime: cftimeinterval = 0  private var nextenemyaddtime: cftimeinterval {     var waittime = score < 10 ? 1.0         : score < 20 ? 0.5         : 0.1     return priorenemyaddtime + waittime }  override func update(currenttime: cftimeinterval) {     if nextenemyaddtime <= currenttime {         priorenemyaddtime = currenttime         addenemy()     } } 

on every frame, check whether it's been long enough since last time added enemy. if so, save current time time of last add, , add enemy.