Simple naive implementation of custom Array-like structure

CustomArray.swift

import Foundation

struct MyArray<Element> : CustomStringConvertible {
    
    var description: String {
        var mutableDescription = "["
        for i in 0..<count {
            mutableDescription += "\"\(elementAtIndex(i)) "
            if i != count - 1 {
                mutableDescription += ", "
            }
        }
        mutableDescription += "]"
        return mutableDescription
    }
    
    private let dataRepresentation: NSMutableData
    
    init() {
        dataRepresentation = NSMutableData()
    }
    
    init(elements: Element ...) {
        self.init(elements: elements)
    }

    init(elements: [Element]) {
        self.init()
        for element in elements {
            append(element)
        }
    }
    
    private let elementSize = sizeof(Element)
    
    var count: Int { return dataRepresentation.length / elementSize }
    
    subscript(index: Int) -> Element {
        get {
            return elementAtIndex(index)
        }
        set {
            insert(newValue, toIndex: index)
        }
    }
    
    func elementAtIndex(index: Int) -> Element {
        let subdata = dataRepresentation.subdataWithRange(NSRange(location: index * elementSize, length: elementSize))
        return UnsafeMutablePointer<Element>(subdata.bytes).memory
    }
    
    mutating func append(element: Element) {
        var copyElement = element
        dataRepresentation.appendBytes(&copyElement, length: elementSize)
    }
    
    mutating func insert(element: Element, toIndex index: Int) {
        var newElement = element
        dataRepresentation.replaceBytesInRange(NSRange(location: index * elementSize, length: 0), withBytes: NSData(bytes: &newElement, length: elementSize).bytes, length: elementSize)
    }
    
    mutating func removeElementAtIndex(index: Int) {
        CFDataDeleteBytes(dataRepresentation, CFRangeMake(index * elementSize, elementSize))
    }
}