Replace characters from set with replacement string

String+Replacement.swift

import Foundation

extension String {
    func replaceCharactersFromSet(characterSet: NSCharacterSet, replacementString: String) -> String {
        let scanner = NSScanner(string: self)
        scanner.charactersToBeSkipped = nil
        
        let sanitizedString = NSMutableString(capacity: self.characters.count)
        
        while(!scanner.atEnd) {
            var buffer: NSString? = ""
            if scanner.scanUpToCharactersFromSet(characterSet, intoString: &buffer), let buffer = buffer {
                sanitizedString.appendString(buffer as String)
            } else {
                scanner.scanLocation = scanner.scanLocation + 1
                sanitizedString.appendString(replacementString as String)
            }
        }
        
        return sanitizedString as String
    }
}

👍

Useful, thanks.