regex.swift

import Foundation


extension NSRegularExpression {
    convenience init(_ pattern: String) {
        do {
            try self.init(pattern: pattern)
        } catch {
            preconditionFailure("Illeagal regular expression: \(pattern).")
        }
    }
    
    func matches(_ string: String) -> Bool {
        let range = NSRange(location: 0, length: string.utf16.count)
        return firstMatch(in: string, options: [], range: range) != nil
    }
}


let testString = "hat"

let range = NSRange(location: 0, length: testString.utf16.count)
let regex = NSRegularExpression("[a-z]at")

regex.firstMatch(in: testString, options: [], range: range) != nil


regex.matches("xxat")

extension String {
    static func ~= (lhs: String, rhs: String) -> Bool {
        guard let regex = try? NSRegularExpression(pattern: rhs) else { return false }
        let range = NSRange(location: 0, length: lhs.utf16.count)
        return regex.firstMatch(in: lhs, options: [], range: range) != nil
    }
}


"https://" ~= "^.*://$"

"cad" ~= "ca[a-z]*d"
"cad" ~= "ca[a-z]+d"
"cad" ~= "ca[a-z]?d"