Helper for working with char ** in Swift

CStringArray.swift

// Copyright © 2015 Indragie Karunaratne. All rights reserved.
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#if os(Linux)
    import Glibc
#else
    import Darwin
#endif

public final class CStringArray {
    public let bufferPointer: UnsafeMutableBufferPointer<UnsafeMutablePointer<Int8>>
    public var pointer: UnsafePointer<UnsafeMutablePointer<Int8>> {
        return UnsafePointer(bufferPointer.baseAddress)
    }
    
    private var stringLengths = [Int]()
    
    public init(_ strings: [String]) {
        let count = strings.count
        let ptr = UnsafeMutablePointer<UnsafeMutablePointer<Int8>>.alloc(count)
        bufferPointer = UnsafeMutableBufferPointer(start: ptr, count: count)
        
        for (index, str) in strings.enumerate() {
            str.withCString { sourcePtr in
                let lengthInBytes = str.nulTerminatedUTF8.count
                let destPtr = UnsafeMutablePointer<Int8>.alloc(lengthInBytes)
                strncpy(destPtr, sourcePtr, lengthInBytes)
                bufferPointer[index] = destPtr
                stringLengths.append(lengthInBytes)
            }
        }
    }
    
    deinit {
        for (ptr, length) in zip(bufferPointer, stringLengths) {
            ptr.destroy()
            ptr.dealloc(length)
        }
        let count = bufferPointer.count
        let ptr = bufferPointer.baseAddress
        ptr.destroy()
        ptr.dealloc(count)
    }
}