Swift DNSPacket parser

DNSPacket.swift

import Foundation
import Darwin
class DNSPacket: NSObject {
    var identifier:UInt16 = 0
    var queryDomains:[String] = []
    var rawData:NSData
//    override init() {
//        
//    }


    init(data:NSData) {
        if data.length < 12 {
            
            NSLog("data error")
        }
       
        let bytes:UnsafePointer<UInt16> =  UnsafePointer<UInt16>.init(data.bytes)
        var p:UnsafePointer<UInt16> = bytes
        identifier = bytes.memory
        p = bytes + 2
        let count:UInt16 = p.memory.bigEndian
        p = p + 4
        var ptr:UnsafePointer<UInt8> = UnsafePointer<UInt8>.init(p)
        let  endptr:UnsafePointer<UInt8> = ptr.advancedBy(data.length-6*2)
        for _ in 0..<count {
            var domainString:String = ""
            var  domainLength = 0
            while (ptr.memory != 0x0) {
                let len = Int(ptr.memory)
                ptr++
                
                if ptr.distanceTo(endptr) < len   {
                    NSLog("error return ")
                }
                let s = NSString.init(bytes: ptr, length: len, encoding: NSUTF8StringEncoding) as! String
                
                domainString = domainString + s + "."
                ptr = ptr + Int(len)
                domainLength += len
                
                domainLength++
            }
            ptr += 3
            if (ptr.distanceTo(endptr) <= 0 ) { NSLog("data error") }
            queryDomains.append(domainString)
        }
        rawData = data
        super.init()
    }
}