Regex not working in swift. Giving an error "invalid regex"

Question

I am trying to get substrings from one string. And for that I am applying regex {[^{]*} But its not working in my swift code and giving me an error "invalid regex". Same regex is working with https://regex101.com/r/B8Gwa7/1. I am using following code to apply regex. I need to get substrings between "{" and "}". Can I get same result without using regex or is there anything wrong with my regex or code?.

static func matches(regex: String, text: String) -> Bool {
        do {
            let regex = try NSRegularExpression(pattern: regex, options: [.caseInsensitive])
            let nsString = text as NSString
            let match = regex.firstMatch(in: text, options: [],
                                         range: NSRange(location: .zero, length: nsString.length))
            return match != nil
        } catch {
            print("invalid regex: \(error.localizedDescription)")
            return false
        }
    }

First of all, you want such regex {[^}]*} Secondly, try escaping characters such as { and } — Michał Turczyn
– Michał Turczyn, Commented Mar 12, 2021 at 7:59
@MichałTurczyn tried using {[^}]*} but still getting same error. — AVR
– AVR, Commented Mar 12, 2021 at 8:01

vadian · Accepted Answer · 2021-03-12 08:10:27Z

2

Curly braces are special characters which have to be escaped

\{[^}]*\}, in a Swift literal string \\{[^}]*\\}

By the way don't use the literal initializer of NSRange to get the length of the string, the highly recommended way is

static func matches(regex: String, text: String) -> Bool {
    do {
        let regex = try NSRegularExpression(pattern: regex, options: .caseInsensitive)
        let match = regex.firstMatch(in: text, options: [],
                                     range: NSRange(text.startIndex..., in: text)
        return match != nil
    } catch {
        print("invalid regex: \(error.localizedDescription)")
        return false
    }
}

edited Mar 12, 2021 at 8:10

answered Mar 12, 2021 at 8:01

vadian

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