How to Wrap for Swift in xcode and have swift display results

//Volume
double Volume()
{
    double vol = 0.0;
  d = sqrt(rad*3);
  c = pow(d, 2);
  a = pow(c, 2);
  v = pow(c, 3);
  s = pow(c, 3)*.25;
  d2 = sqrt(radt*3);
  c2 = pow(d2, 2);
  a2 = pow(c2, 2);
  v2 = pow(c2, 3);
  s2 = pow(c2, 3)*.25;
  u = v2/8;
  sigf = v*u;
  sigg = v/u;
  yd = sqrt(radring*3);
  yc = pow(yd, 2);
  ya = pow(yc, 2);
  yv = pow(yc, 3);
  ys = pow(yc, 3)*.25;
  yr = yc / (radring/2);
  SC = pow(2, sqrt(1*.25)) + rad;
  SCP = (2/(cbrt(1*2))) + rad;
  if (rad > 0)
{
    ES = SC - 1;
    EC = SCP - 1;
}
  colinc = EC*sigf;
  coldec = EC*sigg;
  colplus = colinc+rad;
  colminus = coldec-rad;
  colmul = rad*colinc;
  coldiv = coldec/rad;
  colsqr = pow(EC, rad);
  cbmsatomscale = EC+radms;
  cbmsatombuild = (cbmsatomscale*2.45837792159999990460e21)-(SCP*2.45837792159999990460e21);
  masspound = radms*cbmsatombuild;

  //Volume and Density Transition
  denatom = cbmsatomscale/rad;
  denscalevlmm = (denatom*6022e21)/rad;
  dencenticube = pow(denscalevlmm, 3);
  volmm = mmrad*denscalevlmm;
  volcm = cmrad*dencenticube;
  centigram = volcm/dencenticube;
  inchgram = centigram*16.38706;
  densitypound = masspound/radms;
  //Volume and Density Transition fluid scale (Finite Elaboration)
  denscaleinc = pow(masspound, 2);
  denscaledec = sqrt(denscaleinc);
  denscaleinccb = pow(masspound, 3);
  denscaledeccb = cbrt(denscaleinccb);
  denscalepow = pow(masspound, denscale);
  denscalesqr = sqrt(denscalepow);
  denscalecbr = cbrt(denscalepow);
  return (vol);

}