See Swift 3 example for usage information and notes
func pbkdf2SHA1Calibrate(password:String, salt:[UInt8], msec:Int) -> UInt32 {
let actualRoundCount: UInt32 = CCCalibratePBKDF(
CCPBKDFAlgorithm(kCCPBKDF2),
password.utf8.count,
salt.count,
CCPseudoRandom...