.getBytes() in Swift 1.2 gives trouble - xcode6

Question

In Swift 1.2, I am trying to compile the md5 implementation that I found on rosettacode.
One single line gives me an error and I cannot figure out why.
This is the line:
chunk.getBytes(M[x], range:range)
This is the error I get:
Cannot invoke 'getBytes' with an argument of type'(UInt32, range: _NSRange)'
And this is the context:
// break chunk into sixteen 32-bit words M[j], 0 ≤ j ≤ 15
let wordSize = sizeof(UInt32)
var M:[UInt32] = [UInt32](count: 16, repeatedValue: 0)
for x in 0..<M.count {
var range = NSRange(location:x * wordSize, length: wordSize)
chunk.getBytes(M[x], range:range)
}
(BTW, the same line worked well in the previous version of Swift)
Thanks for any insight!

Answer 1

The code that works in Swift 1.1 is (note the & operator):
chunk.getBytes(&M[x], range:range)
but this does indeed not compile anymore with Swift 1.2.
You can replace the line with the equivalent code
withUnsafeMutablePointer(&M[x]) { chunk.getBytes($0, range:range) }
or use a temporary variable
var tmp = UInt32(0)
chunk.getBytes(&tmp, range:range)
M[x] = tmp
to make it work again.
But note that the loop is actually not needed at all, and your
code can be simplified to
let wordSize = sizeof(UInt32)
var M = [UInt32](count: 16, repeatedValue: 0)
chunk.getBytes(&M, length: M.count * wordSize)
which compiles with Swift 1.1 and 1.2.