A few regex utilities in Swift.

Regex+Utilities.swift

extension NSRegularExpression {
    convenience init(_ pattern: String) {
        do {
            try self.init(pattern: pattern)
        } catch {
            preconditionFailure("Illegal regular expression with pattern: \(pattern)")
        }
    }

    func matches(_ string: String, options: NSRegularExpression.MatchingOptions = []) -> Bool {
        let range = NSRange(location: 0, length: string.utf16.count)
        return firstMatch(in: string, options: options, range: range) != nil
    }
}

extension String {
    static func ~= (lhs: String, rhs: String) -> Bool {
        guard let regex = try? NSRegularExpression(pattern: rhs) else { return false }
        return regex.matches(lhs)
    }
}

Usage:

let regex = NSRegularExpression(#"^@?(\w){1,15}$"#) // Note the lack of `try!` before calling the initializer

let testString: String = "@rogerluan_"
if regex.matches(testString) {
    print("\(testString) matches the regex!)")
}

if testString ~= regex {
    print("\(testString) matches the regex!")
}