Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Handy Regex utility to find and replace matching groups in Swift.
extension String {
/// Finds matching groups and replace them with a template using an intuitive API.
///
/// This example will go through an input string and replace all occurrences of "MyGreatBrand" with "**MyGreatBrand**".
///
/// let regex = try! NSRegularExpression(pattern: #"(MyGreatBrand)"#) // Matches all occurrences of MyGreatBrand
/// someMarkdownDocument.replaceGroups(matching: regex, with: #"**$1**"#) // Surround all matches with **, formatting as bold text in markdown.
/// print(someMarkdownDocument)
///
/// - Parameters:
/// - regex: the regex used to match groups.
/// - template: the template used to replace the groups. Reference groups inside your template using dollar sign symbol followed by the group number, e.g. "$1", "$2", etc.
public mutating func replaceGroups(matching regex: NSRegularExpression, with template: String, options: NSRegularExpression.MatchingOptions = []) {
var replacingRanges: [(subrange: Range<String.Index>, replacement: String)] = []
let matches = regex.matches(in: self, options: options, range: NSRange(location: 0, length: utf16.count))
for match in matches {
var replacement: String = template
for rangeIndex in 1 ..< match.numberOfRanges {
let group: String = (self as NSString).substring(with: match.range(at: rangeIndex))
replacement = replacement.replacingOccurrences(of: "$\(rangeIndex)", with: group)
}
replacingRanges.append((subrange: Range(match.range(at: 0), in: self)!, replacement: replacement))
}
for (subrange, replacement) in replacingRanges.reversed() {
self.replaceSubrange(subrange, with: replacement)
}
}
/// Finds matching groups and replace them with a template using an intuitive API.
///
/// This example will go through an input string and replace all occurrences of "MyGreatBrand" with "**MyGreatBrand**".
///
/// let regex = try! NSRegularExpression(pattern: #"(MyGreatBrand)"#) // Matches all occurrences of MyGreatBrand
/// let result = someMarkdownDocument.replacingGroups(matching: regex, with: #"**$1**"#) // Surround all matches with **, the bold text modifier syntax in markdown.
/// print(result)
///
/// - Parameters:
/// - regex: the regex used to match groups.
/// - template: the template used to replace the groups. Reference groups inside your template using dollar sign symbol followed by the group number, e.g. "$1", "$2", etc.
public func replacingGroups(matching regex: NSRegularExpression, with transformationString: String) -> String {
var mutableSelf = self
mutableSelf.replaceGroups(matching: regex, with: transformationString)
return mutableSelf
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment