Inter-operability of Swift arrays with C?

Question

How can one pass or copy the data in a C array, such as

float foo[1024];

, between C and Swift functions that use fixed size arrays, such as d

Answer 1

I don't think this is easily possible. In the same way as you can't use C style arrays for parameters working with a NSArray.

All C arrays in Swift are represented by an UnsafePointer, e.g. UnsafePointer. Swift doesn't really know that the data are an array. If you want to convert them into a Swift array, you will have create a new object and copy the items there one by one.

let array: Array = [10.0, 50.0, 40.0]

// I am not sure if alloc(array.count) or alloc(array.count * sizeof(Float))
var cArray: UnsafePointer = UnsafePointer.alloc(array.count)
cArray.initializeFrom(array)

cArray.dealloc(array.count)

Edit

Just found a better solution, this could actually avoid copying.

let array: Array = [10.0, 50.0, 40.0]

// .withUnsafePointerToElements in Swift 2.x
array.withUnsafeBufferPointer() { (cArray: UnsafePointer) -> () in
    // do something with the C array
}