Binary gap solution in Swift / https://codility.com/programmers/task/binary_gap/

binary_gap.playground.swift

//: Playground - noun: a place where people can play
//: Binary gap solution for https://codility.com/programmers/task/binary_gap/

import UIKit

// use unsigned
func binary_gap(_ number: UInt) -> UInt {
    var max_gap: UInt = 0
    var current_gap: UInt = 0
    
    var n = number
    
    // division by 2 would produce each of bits right-to-left
    // i.e. 1096 in bin is:
    // 1 0 0 0 1 0 0 1 0 0 0
    // first we divide until we skip all trailing zeroes
    while n > 0 && n % 2 == 0 {
        n /= 2
    }
    
    while n > 0 {
        // we divide first since last loop pretty much should have stumbled upon 1
        n /= 2
        
        // reset counter and save new gap
        if n % 2 == 1 {
            if current_gap > max_gap {
                max_gap = current_gap
            }
            current_gap = 0
        } else {
            // bump counter if we stumble upon 0
            current_gap += 1
        }
    }
    
    return max_gap
}

binary_gap(1096)