Swift iOS Mask a string "Hello" to "Hxxxo" - ios

Question

extension String {
var masked: String {
// some logic which I have to write to mask string.
// I tried following and just shows x 🤦‍♂️
// replacingOccurrences(
// of: ".(.+).",
// with: "x",
// options: .regularExpression,
// range: nil
//)
}
}
let helloWorld = "Hello World"
print("Masked string is - \(helloWorld.masked)")
Expected output is - "Hxxxxxxxxxd"

Answer 1

There is a Regular Expression way with lookaround
extension String {
var masked: String {
replacingOccurrences(
of: "(?!^).(?!$)", // RegEx
with: "x", // Replacement
options: .regularExpression // Option to set RegEx
)
}
}

Answer 2

You can enumerate the string and apply map transform to get the expected output:
extension String {
var masked: String {
self.enumerated().map({ (index, ch) in
if index == 0
|| index == self.count - 1 {
return String(ch)
}
return "x"
}).joined()
}
}
let str = "hello"
print("after masking \(str.masked)") // Output - hxxxo
The map transform will return an array, so use joined() to convert the array back to String. Also, note that you have to typecast ch to String as String(ch) because the type of ch is 'String.Element' (aka 'Character').

Answer 3

extension Sequence {
func replacingEachInteriorElement(with replacement: Element) -> [Element] {
let prefix = dropLast()
return
prefix.prefix(1)
+ prefix.dropFirst().map { _ in replacement }
+ suffix(1)
}
}
extension String {
var masked: Self {
.init( replacingEachInteriorElement(with: "x") )
}
}
"Hello World".masked == "Hxxxxxxxxxd" // true
"H🦾👄🐺🥻🐸🦈🏄‍♂️🍯🪐d".masked == "Hello World".masked // true
"🥮".masked // 🥮
"🥶😎".masked // 🥶😎
[].replacingEachInteriorElement(with: 500) // []

Answer 4

My solution without using Regular Expression:
extension String {
var masked: String {
if self.count < 2 { return self }
var output = self
let range = self.index(after: self.startIndex)..<self.index(before: endIndex)
let replacement = String.init(repeating: "x", count: output.count - 2)
output.replaceSubrange(range, with: replacement)
return output
}
}

Answer 5

So far, I've found following solution.
extension String {
var masked: String {
var newString = ""
for index in 0..<count {
if index != 0 && index != count-1 {
newString.append(contentsOf: "x")
} else {
let array = Array(self)
let char = array[index]
let string = String(char)
newString.append(string)
}
}
return newString
}
}

Answer 6

If you want to leave first and last letters you can use this ->
public extension String {
var masked: String {
return prefix(1) + String(repeating: "x", count: Swift.max(0, count-2)) + suffix(1)
}
}
USAGE
let hello = "Hello"
hello.masked
// Hxxxo
OR
you can pass unmasked character count ->
public extension String {
func masked(with unmaskedCount: Int) -> String {
let unmaskedPrefix = unmaskedCount/2
return prefix(unmaskedPrefix) + String(repeating: "x", count: Swift.max(0, count-unmaskedPrefix)) + suffix(unmaskedPrefix)
}
}
USAGE
let hello = "Hello"
hello.masked(with: 2)
// Hxxxo
let number = "5555555555"
number.masked(with: 4)
// 55xxxxxx55