检测SKAction是否已完成运行，Swift

Question

I want to change the value of a variable after an action has been run and not during it is running. This is my code:

   override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {

    if gameNotStarted {
        if firePosition.x != 320 || firePosition.y > 280 {  
            fire.runAction(fireButtonReturn)
            iapButton.runAction(iapButtonReturn)
            aboutButton.runAction(abtButtonReturn)

            if fire.hasActions() == false {
                println("has no actions")
                firePosition.x = 320
                firePosition.y = 280
            } 
        }       
    }
}

The three actions I am running have exactly the same duration so I only need one to check if they have finished running. After they have finished running I want to change the value of firePosition.x and firePosition.y . It is very important that fire position values change exactly after the action has been run and absolutely not before the actions are done running.

However with my current code I never run the if fire.hasActions() ... part according to results and console. I found similar questions, they were in obj-c. Thanks for your help.

Answer 1

You should use a completion-handler for your kind of problem:

//Run the action
iapButton.runAction(iapButtonReturn,
    //After action is done, just call the completion-handler.
    completion: {
        firePosition.x = 320
        firePosition.y = 280
    }
)

Or you could use a SKAction.sequence and add your actions inside a SKAction.block :

var block = SKAction.runBlock({
    fire.runAction(fireButtonReturn)
    iapButton.runAction(iapButtonReturn)
    aboutButton.runAction(abtButtonReturn)
})

var finish = SKAction.runBlock({
    firePosition.x = 320
    firePosition.y = 280
})

var sequence = SKAction.sequence([block, SKAction.waitForDuration(yourWaitDuration), finish])

self.runAction(sequence)

Answer 2

you should use a completion handler:

fire.runAction(fireButtonReturn,
    completion: {
        println("has no actions")
        firePosition.x = 320
        firePosition.y = 280
    }
)

the problem with your solution is, that the action is initiated with the runAction call but then runs in the background while the main thread continues the execution (and therefore reaches it before the action is finished).

Answer 3

extension SKNode {
    func actionForKeyIsRunning(key: String) -> Bool {
        if self.actionForKey(key) != nil {
            return true
        } else {
            return false
        }
    }
}

You can use it :

if myShip.actionForKeyIsRunning("swipedLeft") {
   print("swipe in action..")
}