Make sure regex matches the entire string with Swift regex

Question

How to check whether a WHOLE string can be matches to regex? In Java is method String.matches(regex)

Answer 1

Swift extract regex matches

with little bit of edit

import Foundation

func matches(for regex: String, in text: String) -> Bool {
    do {
        let regex = try NSRegularExpression(pattern: regex)
        let nsString = text as NSString
        let results = regex.matches(in: text, range: NSRange(location: 0, length: nsString.length))
        return !results.isEmpty
    } catch let error {
        print("invalid regex: \(error.localizedDescription)")
        return false
    }
}

Example usage from link above:

let string = "19320"
let matched = matches(for: "^[1-9]\\d*$", in: string)
print(matched) // will match

let string = "a19320"
let matched = matches(for: "^[1-9]\\d*$", in: string)
print(matched) // will not match

Answer 2

What you are looking for is range(of:options:range:locale:) then you can then compare the result of range(of:option:) with whole range of comparing string..

Example:

let phoneNumber = "(999) 555-1111"
let wholeRange = phoneNumber.startIndex..<phoneNumber.endIndex
if let match = phoneNumber.range(of: "\\(?\\d{3}\\)?\\s\\d{3}-\\d{4}", options: .regularExpression), wholeRange == match {
    print("Valid number")
}
else {
    print("Invalid number")
}
//Valid number

Edit: You can also use NSPredicate and compare your string with evaluate(with:) method of its.

let pattern = "^\\(?\\d{3}\\)?\\s\\d{3}-\\d{4}$"
let predicate = NSPredicate(format: "self MATCHES [c] %@", pattern)
if predicate.evaluate(with: "(888) 555-1111") {
    print("Valid")
}
else {
    print("Invalid")
}

Answer 3

You need to use anchors, ^ (start of string anchor) and $ (end of string anchor), with range(of:options:range:locale:), passing the .regularExpression option:

import Foundation

let phoneNumber = "123-456-789"
let result = phoneNumber.range(of: "^\\d{3}-\\d{3}-\\d{3}$", options: .regularExpression) != nil
print(result)

Or, you may pass an array of options, [.regularExpression, .anchored], where .anchored will anchor the pattern at the start of the string only, and you will be able to omit ^, but still, $ will be required to anchor at the string end:

let result = phoneNumber.range(of: "\\d{3}-\\d{3}-\\d{3}$", options: [.regularExpression, .anchored]) != nil

See the online Swift demo

Also, using NSPredicate with MATCHES is an alternative here:

The left hand expression equals the right hand expression using a regex-style comparison according to ICU v3 (for more details see the ICU User Guide for Regular Expressions).

MATCHES actually anchors the regex match both at the start and end of the string (note this might not work in all Swift 3 builds):

let pattern = "\\d{3}-\\d{3}-\\d{3}"
let predicate = NSPredicate(format: "self MATCHES [c] %@", pattern)
let result = predicate.evaluate(with: "123-456-789")