PhoneFormatter for eureka.

PhoneFormatter.swift

public class PhoneFormatter: Formatter, FormatterProtocol {

    override public func getObjectValue(
        _ obj: AutoreleasingUnsafeMutablePointer<AnyObject?>?,
        for string: String,
        errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
        guard obj != nil else { return false }
        let str = string.components(separatedBy: CharacterSet.decimalDigits.inverted).joined(separator: "")
        obj?.pointee = str as AnyObject
        return true
    }

    public override func string(for obj: Any?) -> String? {
        guard let oldString = obj as? String else {
            return nil
        }

        return getNewFormattedString(from: oldString)
    }

    public func getNewPosition(
        forPosition position: UITextPosition,
        inTextInput textInput: UITextInput,
        oldValue: String?,
        newValue: String?
        ) -> UITextPosition {

        let offset = ((newValue?.count ?? 0) - (oldValue?.count ?? 0))
        return textInput.position(from: position, offset: offset) ?? position
    }

    private func getNewFormattedString(from oldString: String) -> String {

        let oldString = oldString as NSString
        let length = oldString.length
        let formattedString = NSMutableString()
        var index = 0 as Int

        if (length - index) > 2 {
            let areaCode = oldString.substring(with: NSRange(location: index, length: 2))
            formattedString.appendFormat("(%@) ", areaCode)
            index += 2
        }

        if length - index > 2 {
            let prefix = oldString.substring(with: NSRange(location: index, length: 5))
            formattedString.appendFormat("%@-", prefix)
            index += 5
        }
        let remainder = oldString.substring(from: index)
        formattedString.append(remainder)

        return formattedString as String
    }
}