Why is Add Emitter to Node not happening immediately?

Why is Add Emitter to Node not happening immediately?

Within an extension to GameViewController I have:

func  addEmitterToNode(_ particleName: String,
                       _ theNode:SKSpriteNode) {
            
    if let emitter = SKEmitterNode(fileNamed: particleName) {
        emitter.name = "emitter"
        emitter.position = CGPoint(x: 0, y: 0)   // = at center
        theNode.addChild(emitter)
    }
    
}   // addEmitterToNode

Here is the func (extension to GameViewController) wherein I call the above. The problem is the explosion sound plays but the smoke particle emitter is not immediately added.

func increaseSpeed() {
    
    if thisSpeed > maxSpeed {
        pauseGame()   // sets myTrain.isPaused = true
        
        playSound(theSoundName: "explosion")
        addEmitterToNode("smokeParticle.sks", myTrain)
        trainHasCrashed = true
    }
    
}   // increaseSpeed

What I do not understand is that the following within GameScene's sceneDidLoad, the smoke particle emitter is added =

override func sceneDidLoad() {
    if itsGameViewController.trainHasCrashed {
        itsGameViewController.addEmitterToNode("smokeParticle.sks",
                                               myTrain)
    }
 }