Have a solution but need to optimize  func reverse(stringWithIgnoreSymbols: String, ignoreSymbols: String) -> String {     let words = stringWithIgnoreSymbols.components(separatedBy: " ")     var wordsPositions: [[String:[Int]]] = []     for (index, word) in words.enumerated() {       wordsPositions.append([:])       for ignoredCharacter in ignoreSymbols {         for (indx, words) in word.enumerated() {           if words == ignoredCharacter {             if wordsPositions[index][String(ignoredCharacter)] == nil {               wordsPositions[index][String(ignoredCharacter)] = [indx]             } else {               wordsPositions[index][String(ignoredCharacter)]!.append(indx)             }           }         }       }     }     var newTextArray = words     for (i, _) in words.enumerated() {       for ignoredCharacter in ignoreSymbols {         newTextArray[i] = newTextArray[i].replacingOccurrences(of: String(ignoredCharacter), with: "")       }     }     newTextArray = newTextArray.map() { String($0.reversed()) }     for i in 0..<words.count {       var orderedArray = [(Int, String)] ()       for toRestore in wordsPositions[i] {         for item in toRestore.value {           orderedArray.append((item, toRestore.key))         }         orderedArray = orderedArray.sorted() { $0.0 < $1.0 }       }       for (index, str) in orderedArray {         let posIndex = newTextArray[i].index(newTextArray[i].startIndex, offsetBy: index)         let char = str[0]         newTextArray[i].insert(char, at: posIndex)       }     }     return newTextArray.joined(separator: " ")   } private extension StringProtocol {   subscript(offset: Int) -> Character {     self[index(startIndex, offsetBy: offset)]   } }

Second example final class ExceptionRuleReverseManager {   var exceptionElements = String()       func reverse(string: String) -> String {     let words = string.components(separatedBy: " ")     var result = [String]()     for word in words {       result.append(rearrangeWord(word))     }     return String(result.joined(separator: " "))   }       private func rearrangeWord(_ word: String) -> String {     var arrayOfCharacters = Array(word)     if var firstElementIndex = arrayOfCharacters.indices.first,       var secondElementIndex = arrayOfCharacters.indices.last {       while firstElementIndex < secondElementIndex {         if isException(element: word[firstElementIndex]) { // If first element is exception - skip it           firstElementIndex += 1 // If second element is exception - skip it         } else if isException(element: word[secondElementIndex]) {           secondElementIndex -= 1         } else { // If both elements are not exceptions - swap them           arrayOfCharacters.swapAt(firstElementIndex, secondElementIndex)           firstElementIndex += 1           secondElementIndex -= 1         }       }     }     return String(arrayOfCharacters)   }       private func isException(element: String.Element) -> Bool {     return exceptionElements.contains(element)   } } extension String {   subscript (index: Int) -> String.Element {     let stringIndex = self.index(self.startIndex, offsetBy: index)     return self[stringIndex]   } } var ReverseManager = ExceptionRuleReverseManager() ReverseManager.exceptionElements = "A2" var input = "Alloha 234" var result = ReverseManager.reverse(string: input) print(result) // result = Aaholl 243 ReverseManager.exceptionElements = "4B" input = "Ball4 456" result = ReverseManager.reverse(string: input) // result = Blla4 465