SceneKit -– How to get animations for a .dae model?

Question

Ok, I am working with ARKit and SceneKit here and I am having trouble looking at the other questions dealing with just SceneKit trying to have a model in .dae forma

Answer 1

At first I should confirm that CoreAnimation framework and some of its methods like animation(forKey:) instance method are really deprecated in iOS and macOS. But some parts of CoreAnimation framework are now implemented into SceneKit and other modules. In iOS 11+ and macOS 10.13+ you can use SCNAnimation class:

let animation = CAAnimation(scnAnimation: SCNAnimation())

and here SCNAnimation class has three useful initializers:

SCNAnimation(caAnimation: CAAnimation())
SCNAnimation(contentsOf: URL())
SCNAnimation(named: String())

In addition I should add that you can use not only animations baked in .dae file format, but also in .abc, .scn and .usdz.

Also, you can use SCNSceneSource class (iOS 8+ and macOS 10.8+) to examine the contents of a SCNScene file or to selectively extract certain elements of a scene without keeping the entire scene and all the assets it contains.

Here's how a code with implemented SCNSceneSource might look like:

@IBOutlet var sceneView: ARSCNView!
var animations = [String: CAAnimation]()
var idle: Bool = true

override func viewDidLoad() {
    super.viewDidLoad()
    sceneView.delegate = self

    let scene = SCNScene()
    sceneView.scene = scene
    
    loadMultipleAnimations()
}

func loadMultipleAnimations() {

    let idleScene = SCNScene(named: "art.scnassets/model.dae")!
    
    let node = SCNNode()
    
    for child in idleScene.rootNode.childNodes {
        node.addChildNode(child)
    }       
    node.position = SCNVector3(0, 0, -5)
    node.scale = SCNVector3(0.45, 0.45, 0.45)
    
    sceneView.scene.rootNode.addChildNode(node)
    
    loadAnimation(withKey: "walking", 
                sceneName: "art.scnassets/walk_straight", 
      animationIdentifier: "walk_version02")
}

...

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 animationObj = sceneSource?.entryWithIdentifier(animationIdentifier, 
                                                 withClass: CAAnimation.self) {
        animationObj.repeatCount = 1
        animationObj.fadeInDuration = CGFloat(1)
        animationObj.fadeOutDuration = CGFloat(0.5)

        animations[withKey] = animationObj
    }
}

...

func playAnimation(key: String) {

    sceneView.scene.rootNode.addAnimation(animations[key]!, forKey: key)
}