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Awesome Open Source

by Crossroad Labs


🐧 linux: ready GitHub license Build Status GitHub release Carthage compatible CocoaPods version Platform OS X | iOS | tvOS | watchOS | Linux

Advanced regular expressions for Swift


Regex library was mainly introduced to fulfill the needs of Swift Express - web application server side framework for Swift.

Still we hope it will be useful for everybody else.

Happy regexing ;)


  • [x] Deep Integration with Swift
    • [x] =~ operator support
    • [x] Swift Pattern Matching (aka switch operator) support
  • [x] Named groups
  • [x] Match checking
  • [x] Extraction/Search functions
  • [x] Replace functions
    • [x] With a pattern
    • [x] With custom replacing function
  • [x] Splitting with a Regular Expression
    • [x] Simple
    • [x] With groups
  • [x] String extensions
  • [x] Supports grapheme clusters 👨‍👩‍👧


Path to Regex converter is available as a separate library here: PathToRegex

This one allows using path patterns like /folder/*/:file.txt or /route/:one/:two to be converted to Regular Expressions and matched against strings.

Getting started


Package Manager

Add the following dependency to your Package.swift:

.Package(url: "", majorVersion: 1)

Run swift build and build your app.


Add the following to your Podfile:

pod 'CrossroadRegex'

Make sure that you are integrating your dependencies using frameworks: add use_frameworks! to your Podfile. Then run pod install.


Add the following to your Cartfile:

github "crossroadlabs/Regex"

Run carthage update and follow the steps as described in Carthage's README.


  1. Download and drop /Regex folder in your project.
  2. Congratulations!


Hello Regex:

All the lines below are identical and represent simple matching. All operators and matches function return Bool

//operator way, can match either regex or string containing pattern
"l321321alala" =~ "(.+?)([123]*)(.*)".r
"l321321alala" =~ "(.+?)([123]*)(.*)"

//similar function

Operator !~ returns true if expression does NOT match:

"l321321alala" !~ "(.+?)([123]*)(.*)".r
"l321321alala" !~ "(.+?)([123]*)(.*)"
//both return false

Swift Pattern Matching (aka switch keyword)

Regex provides very deep integration with Swift and can be used with the switch keyword in the following way:

let letter = "a"
let digit = "1"
let other = "!"

//you just put your string is a regular Swift's switch to match to regular expressions
switch letter {
	//note .r after the string literal of the pattern
	case "\\d".r: print("digit")
	case "[a-z]".r: print("letter")
	default: print("bizarre symbol")

switch digit {
	case "\\d".r: print("digit")
	case "[a-z]".r: print("letter")
	default: print("bizarre symbol")

switch other {
	//note .r after the string literal of the pattern
	case "\\d".r: print("digit")
	case "[a-z]".r: print("letter")
	default: print("bizarre symbol")

The output of the code above will be:

bizarre symbol

Accessing groups:

// strings can be converted to regex in Scala style .r property of a string
let digits = "(.+?)([123]*)(.*)".r?.findFirst(in: "l321321alala")?.group(at: 2)
// digits is "321321" here

Named groups:

let regex:RegexType = try Regex(pattern:"(.+?)([123]*)(.*)",
                                        groupNames:"letter", "digits", "rest")
let match = regex.findFirst(in: "l321321alala")
if let match = match {
	let letter = "letter")
	let digits = "digits")
	let rest = "rest")
	//do something with extracted data


let replaced = "(.+?)([123]*)(.*)".r?.replaceAll(in: "l321321alala", with: "$1-$2-$3")
//replaced is "l-321321-alala"

Replace with custom replacer function:

let replaced = "(.+?)([123]+)(.+?)".r?.replaceAll(in: "l321321la321a") { match in
	if 1) == "l" {
		return nil
	} else {
		return match.matched.uppercaseString
//replaced is "l321321lA321A"


In the following example, split() looks for 0 or more spaces followed by a semicolon followed by 0 or more spaces and, when found, removes the spaces from the string. nameList is the array returned as a result of split().

let names = "Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand"
let nameList = names.split(using: "\\s*;\\s*".r)
//name list contains ["Harry Trump", "Fred Barney", "Helen Rigby", "Bill Abel", "Chris Hand"]

Split with groups:

If separator contains capturing parentheses, matched results are returned in the array.

let myString = "Hello 1 word. Sentence number 2."
let splits = myString.split(using: "(\\d)".r)
//splits contains ["Hello ", "1", " word. Sentence number ", "2", "."]


You can view the CHANGELOG as a separate document here.


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