how to trigger sequence of animations in swift - ios

Question

In Swift 4 i am loaded/holding a set of animations from dae files in an array:
var animations = [String: CAAnimation]()
loadAnimation(withKey: "stepL", sceneName: "art.scnassets/StepL", animationIdentifier: "StepL-1")
loadAnimation(withKey: "stepR", sceneName: "art.scnassets/StepR", animationIdentifier: "StepR-1")
func loadAnimation(withKey: String, sceneName:String, animationIdentifier:String) {
let sceneURL = Bundle.main.url(forResource: sceneName, withExtension: "dae")
let sceneSource = SCNSceneSource(url: sceneURL!, options: nil)
if let animationObject = sceneSource?.entryWithIdentifier(animationIdentifier, withClass: CAAnimation.self) {
// The animation will only play once
animationObject.repeatCount = 1
// To create smooth transitions between animations
animationObject.fadeInDuration = CGFloat(0.8)
animationObject.fadeOutDuration = CGFloat(0.6)
// Store the animation for later use
animations[withKey] = animationObject
}
}
Later on i am playing the animation by adding it to my scene:
func playAnimation(key: String) {
print("fire animation: " + key)
scnView.scene?.rootNode.addAnimation(animations[key]!, forKey: key)
}
This seems to work when doing them individually from touches, but i want to be able to trigger a sequence of these with very specific timing.
I've tried building a loop and sending them off to a DispatchQueue with specific timing outlined:
var delaytime = state.steptime!
for _ in 0..<state.trCount! {
for wSide in state.walkSeq! {
walkQ.asyncAfter(deadline: .now() + delaytime){
self.playAnimation(key: wSide)
}
delaytime += state.steptime! + 1.0
}
}
And i've tried a similar, but slightly different approach using wallDeadline:
let wt = DispatchWallTime.now() + state.pausetime!
//build sequence
var train_seq = [(name:"stepL", time:wt), (name:"stepR",time:wt + state.pausetime! + state.steptime!)]
for _ in 0..<state.trCount! {
let lasttime = train_seq[ train_seq.count - 1 ].time
train_seq += [(name:"stepL", time:lasttime + state.steptime!)]
train_seq += [(name:"stepR", time:lasttime + state.pausetime! + state.steptime!)]
}
//send it
for i in 0..<train_seq.count {
walkQ.asyncAfter(wallDeadline: train_seq[i].time){
self.playAnimation(key: train_seq[i].name)
}
}
What inevitably happens is that the first few run as expected, then around the 4th set of sequences they start to stack on top of each other and fire at the same time, no longer adhering to the timing that i've defined
What is the best way to trigger animations in a sequence on an expected timeline? Is there a way to pause/sleep a loop until the previous animation stops, then trigger the next in the series?
Thanks!

Answer 1

i ended up making a sequence of SCNActions in the order i needed, including a wait
var seq = [SCNAction]()
for _ in 0..<state.trCount!{
let act1 = SCNAction.run {_ in
self.playAnimation(key: "stepL")
}
seq.append(act1)
let act2 = SCNAction.wait(duration: state.steptime!)
seq.append(act2)
let act3 = SCNAction.run { _ in
self.playAnimation(key: "stepR")
}
seq.append(act3)
seq.append(act2)
let act4 = SCNAction.run { _ in
self.playAnimation(key: "idle")
}
seq.append(act4)
let act5 = SCNAction.wait(duration: state.pausetime!)
seq.append(act5)
}
let sequence = SCNAction.sequence(seq)
scnView.scene?.rootNode.runAction(sequence, completionHandler:nil )