Author: Eric Tatham

To find a 3D node pointed to by the user in SceneKit, add a tap gesture recogniser in ViewDidLoad()

  let fingerTap = UITapGestureRecognizer(target: self, action: "handleTap:")
  self.view.addGestureRecognizer(fingerTap)

And here’s a simple handler:

func handleTap(sender: UIGestureRecognizer)
{
    let p = sender.locationInView(self.sceneView)

    let hitResults = self.sceneView.hitTest(p, options: nil)

    if let results = hitResults {
        if (results.count > 0) {
            let result: SCNHitTestResult = results[0] as! SCNHitTestResult
             println("Hit \(result)")
        }

     }
}

I recently needed to load a Collada file into SceneKit and have a short animation play once as soon as the file was loaded.

The Collada file with animation had to be exported from Maya and the initial loading and playing was very straightforward.

func sceneSetup() {
    let scene = SCNScene(named: "Scenes.scnassets/test.dae")
    sceneView.scene = scene
    sceneView.autoenablesDefaultLighting = true
}

However, the animation looped continually.

I not sure this is the best fix but iterating through all possible node animations and setting the repeatCount to 1 fixed the problem.

func sceneSetup() {
    let scene = SCNScene(named: "Scenes.scnassets/test.dae")

    //Get all the child nodes
    let children = scene?.rootNode.childNodes
    
    //Initialise the count of child nodes to zero
    var childCount = 0

    //Iterate through the child nodes
    if let theChildren = children {
        for child in theChildren {
            let keys = child.animationKeys() //get all the animation keys

            //Iterate through the keys and get each animation
            if let theKeys = keys {
                for key in theKeys {
                    let animation = child.animationForKey(key as! String)
                    //Set the repeatCount to 1
                    animation.repeatCount = 1

                    //Write the new animation back
                    scene?.rootNode.childNodes[childCount].removeAnimationForKey(key as! String)
                    scene?.rootNode.childNodes[childCount].addAnimation(animation, forKey: key as! String)
                }
            }
            //Increment the childCount
            childCount++
         }
     }
     sceneView.scene = scene
     sceneView.autoenablesDefaultLighting = true
}

A Singleton is a design pattern that only allows the instantiation of a single instance of a class.

Here’s a simple way of setting up a Singleton in Swift.

let sharedThing = MySingleton()

class MySingleton {
    var name = "Eric"
}

This can be accessed anywhere in your code.

sharedThing.name has default initialisation value “Eric” and can be set with a line such as;

    sharedThing.name = "Lynda"

A lot less typing than was needed to do the same thing in Objective C !

Seems to be a problem when trying to set a UISlder’s thumb tint in the Attribute Inspector as well as in code. The colour of the thumb stays white whatever colour it is set to. A work-around appears to be to assign an image first. Simple enough to assign it’s existing image and then the tint works when set programmatically.

UISlider.appearance().setThumbImage(self.alphaSlider.currentThumbImage, forState: .Normal)

self.alphaSlider.thumbTintColor = UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0)

Strange!