What is the swift equivalent of this cast?

Question

I want to convert this into swift, or at least find something that does the same thing.

 size_t width = CGImageGetWidth(spriteImage);
 size_t height = CGImageGetHeight(spriteImage);

 GLubyte * spriteData = (GLubyte *) calloc(width*height*4, sizeof(GLubyte));

I need to initialize the spriteData pointer in swift of the right size.

Answer 1

The first two of those are of type size_t, which maps to Uint in Swift, and the last is GLubyte, which maps to UInt8. This code will initialize spriteData as an array of GLubyte, which you could pass to any C function that needs an UnsafeMutablePointer<GLubyte> or UnsafePointer<GLubyte>:

let width = CGImageGetWidth(spriteImage)
let height = CGImageGetHeight(spriteImage)    
var spriteData: [GLubyte] = Array(count: Int(width * height * 4), repeatedValue: 0)

What do you need to do with spriteData?

Answer 2

The straightforward way is:

var spriteData = UnsafeMutablePointer<GLubyte>.alloc(Int(width * height * 4))

Note that, if you did this, you have to dealloc it manually.

spriteData.dealloc(Int(width * height * 4))

/// Deallocate `num` objects.
///
/// :param: num number of objects to deallocate.  Should match exactly
/// the value that was passed to `alloc()` (partial deallocations are not
/// possible).