binary search in array of strings sorted alphabetically

BinarySearchString.swift

var arr = ["a", "abc", "aabc", "aabbc", "aaabbbcc", "bacc", "bbcc", "bbbccc", "cb", "cbb", "cbbc", "d" , "defff", "deffz"]


func binarySearch(_ array: [String], value: String) -> String {
    
    var firstIndex = 0
    var lastIndex = array.count - 1
    var wordToFind = "Not founded"
    var count = 0
    
    while firstIndex <= lastIndex {
        
        count += 1
        let middleIndex = (firstIndex + lastIndex) / 2
        let middleValue = array[middleIndex]
        
        if middleValue == value {
            wordToFind = middleValue
            return wordToFind
        }
        if value.localizedCompare(middleValue) == ComparisonResult.orderedDescending {
            firstIndex = middleIndex + 1
        }
        if value.localizedCompare(middleValue) == ComparisonResult.orderedAscending {
            print(middleValue)
            lastIndex = middleIndex - 1
        }
    }
    return wordToFind
}
//print d
print(binarySearch(arr, value: "d"))