Swift chaining optionals - swift

Question

I'm running Yosemite public beta & Xcode6 Beta 4
Based on the OSX SceneKit template, I'm trying to determine what node was clicked on. Here is the mouseDown function, mostly from the template code.
The comment labeled #1 works, which if great, but I'm trying to understand why the code comments #2, #3, and #4 don't compile, or what the errors are really telling me.
Searching the errors I'm not finding results that appear to apply to my case.
the error for #2 seems to usually apply to type casting, and I wouldn't think there is any type casting going on here.
the error for #3 has me totally lost.
and the error for #4 seems like SCNNode doesn't have a name property, but it certainly does.
override func mouseDown(theEvent: NSEvent) {
/* Called when a mouse click occurs */
// check what nodes are clicked
let p = gameView.convertPoint(theEvent.locationInWindow, fromView: nil)
let hitResults = gameView.hitTest(p, options: nil)
// check that we clicked on at least one object
if (hitResults.count > 0){
// retrieved the first clicked object
let result: AnyObject = hitResults[0]
// #1 This works
if let myNode: SCNNode = result.node? {
if myNode.name? == "Die" {
println("Node is named Die")
}
}
// #2 This does not work
// error: Could not find an overload for the 'node' that accepts the supplied arguments
if let myNode = result.node? {
if myNode.name? == "Die" {
println("Node is named Die")
}
}
// #3 This does not work either
// error: Type 'String?' does not confrom to protocol '_RawOptionSet'
if result.node?.name? == "Die" {
println("Node is named Die")
}
// #4 This does not work either
// error: 'SCNNode!' does not have a member named 'name'
if let myName = result.node?.name? {
if myName == "Die" {
println("Node is named Die")
}
}
// get its material
let material = result.node!.geometry.firstMaterial;
// highlight it
SCNTransaction.begin()
SCNTransaction.setAnimationDuration(0.5)
// on completion - unhighlight
SCNTransaction.setCompletionBlock() {
SCNTransaction.begin()
SCNTransaction.setAnimationDuration(0.5)
material.emission.contents = NSColor.blackColor()
SCNTransaction.commit()
}
material.emission.contents = NSColor.redColor()
SCNTransaction.commit()
}
super.mouseDown(theEvent)
}

Answer 1

The failures of #2, #3, and #4 are all because of the lack of type. You say:
the error for #2 seems to usually apply to type casting, and I wouldn't think there is any type casting going on here.
However, you declared result to be AnyObject while you're attempting to access it as an SCNNode, so there's certainly some type cast that needs to happen.
I've seen this before as well working with dictionaries. Not only did I get explicit about the type, I also tested the type beforehand:
var item: AnyObject? = nil
item = map["SWLFlexFormat"]
if let value: AnyObject = item {
configuration.formatter = getConfiguredFlexFormatter(configuration, item: value);
}
func getConfiguredFlexFormatter(configuration: LoggerConfiguration, item: AnyObject) -> LogFormatter? {
if let formatString: String = item as? String {
var formatter = FlexFormatter.logFormatterForString(formatString);
return formatter
}
return nil
}