https://stackoverflow.com/q/78575797/1271826

EmailRegex.swift

let emailRegex = /((?:[a-z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+\/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*"))@((?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\]))/

let redactText = "…"
let maxUserNameLength = 24

func redactEmail(for line: String) -> String {
    line.replacing(emailRegex) { match in
        let (_, name, domain) = match.output
        // If the username is too long, it might be a false positive for an email.
        return name.count > maxUserNameLength ? "\(name)@\(domain)" : redactText
    }
}

let candidate = "Claude’s email is [email protected], and his phone number is 555-1212."
print(redactEmail(for: candidate))

The output:

Claude’s email is …, and his phone number was 555-1212.