hamming-distance-8.swift

func calculateHammingDistance(x: Int, y: Int) -> Int {
  
  // Step 1: Find different bits
  let signedDifferentBits = x ^ y
  
  // We bitcast Int to UInt to allow the algorithm work correctly also for negative numbers.
  var differentBits: UInt = unsafeBitCast(signedDifferentBits, to: UInt.self)
    
  // Step 2: Count them
  var counter = 0
  
  // Until there are some bits set to '1' in differentBits.
  while differentBits > 0 {
  
      // Mask differentBits with number 1 aka 00000001.
      // By doing this, we set all bits of differentBits 
      // but the last one to zero.
      let maskedBits = differentBits & 1 

      // If the last bit is not zero,
      if maskedBits != 0 {
          // increment the counter.
          counter += 1     
      }
  
      // Shift bits in differentBits to the right.
      differentBits = differentBits >> 1
  }
  
  // We're done, return the number of 1s we've found.
  return counter
}