Formatting Phone number in Swift

Question

I\'m formatting my textfiled text once the user start typing the phone number into this format type 0 (555) 444 66 77 and it is working fine but once I get the

Answer 1

Really simple solution:

extension String {
    func applyPatternOnNumbers(pattern: String, replacmentCharacter: Character) -> String {
        var pureNumber = self.replacingOccurrences( of: "[^0-9]", with: "", options: .regularExpression)
        for index in 0 ..< pattern.count {
            guard index < pureNumber.count else { return pureNumber }
            let stringIndex = String.Index(encodedOffset: index)
            let patternCharacter = pattern[stringIndex]
            guard patternCharacter != replacmentCharacter else { continue }
            pureNumber.insert(patternCharacter, at: stringIndex)
        }
        return pureNumber
    }
}

Usage:

guard let text = textField.text else { return }
textField.text = text.applyPatternOnNumbers(pattern: "+# (###) ###-####", replacmentCharacter: "#")