pointers - Swift convert string to UnsafeMutablePointer<Int8>

Question

I have a C function mapped to Swift defined as:

func swe_set_eph_path(path: UnsafeMutablePointer<Int8>) -> Void

I am trying to pass a path to the function and have tried:

        var path = [Int8](count: 1024, repeatedValue: 0);
        for i in 0...NSBundle.mainBundle().bundlePath.lengthOfBytesUsingEncoding(NSUTF16StringEncoding)-1
        {
            var range = i..<i+1
            path[i] = String.toInt(NSBundle.mainBundle().bundlePath[range])
        }
        println("(path)")
        swe_set_ephe_path(&path)

but on the path[i] line I get the error:

'subscript' is unavailable: cannot subscript String with a range of Int

swe_set_ephe_path(NSBundle.mainBundle().bundlePath)

nor

swe_set_ephe_path(&NSBundle.mainBundle().bundlePath)

don't work either

Besides not working, I feel there has got to be a better, less convoluted way of doing this. Previous answers on StackOverflow using CString don't seem to work anymore. Any suggestions?

Answer 1

Previous answers on StackOverflow using CString don't seem to work anymore

Nevertheless, UnsafePointer<Int8> is a C string. If your context absolutely requires an UnsafeMutablePointer, just coerce, like this:

let s = NSBundle.mainBundle().bundlePath
let cs = (s as NSString).UTF8String
var buffer = UnsafeMutablePointer<Int8>(cs)
swe_set_ephe_path(buffer)

Of course I don't have your swe_set_ephe_path, but it works fine in my testing when it is stubbed like this:

func swe_set_ephe_path(path: UnsafeMutablePointer<Int8>) {
    println(String.fromCString(path))
}