Custom SceneKit Geometry in Swift on iOS not working but equivalent Objective C code does

Question

I am keen to adopt the new Swift language as this seems to be the way forward with Apple development. I have also been impressed with the new SceneKit support in iOS 8. I wo

Answer 1

Well, the two pieces of code doesn't translate exactly to one another. The int in C is not the same as Int in Swift. It's actually called CInt in Swift:

/// The C 'int' type.
typealias CInt = Int32

If you change both occurrences to use CInt instead, the error message that you previously got goes away (at least for me in an OS X Playground. However, it still doesn't render anything for me.

I don't think sizeofValue is used to return the size of an array. It looks to me like it's returning the size of the pointer:

let indexes: CInt[] = [0, 1, 2]
sizeofValue(indexes)                   // is 8
sizeof(CInt)                           // is 4
sizeof(CInt) * countElements(indexes)  // is 12

// compare to other CInt[]
let empty: CInt[] = []
let large: CInt[] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

sizeofValue(indexes)                   // is 8 (your array of indices again)
sizeofValue(empty)                     // is 8
sizeofValue(large)                     // is 8

So, for me the following code works (I've put the arguments on different lines to make it easier to point out my changes):

let src = SCNGeometrySource(vertices: &verts, count: 3)
let indexes: CInt[] = [0, 1, 2] // Changed to CInt

let dat  = NSData(
    bytes: indexes,
    length: sizeof(CInt) * countElements(indexes) // Changed to size of CInt * count
)
let ele = SCNGeometryElement(
    data: dat,
    primitiveType: .Triangles,
    primitiveCount: 1,
    bytesPerIndex: sizeof(CInt) // Changed to CInt
)
let geo = SCNGeometry(sources: [src], elements: [ele])

let nd = SCNNode(geometry: geo)
scene.rootNode.addChildNode(nd)

With this result: