Binary Search using Range.swift

var range = 0...elements.count
while range.count > 1 {
    let pivot = (range.lowerBound + range.upperBound)/2
    if areInIncreasingOrder(elements[pivot], element) {
        range = (pivot + 1)...range.upperBound
    } else if areInIncreasingOrder(element, elements[pivot]) {
        range = range.lowerBound...pivot
    } else {
        range = pivot...pivot
    }
}