String extension with separate function to check validity of a string.

StringType.swift

//  StringType.swift
//
//  Created by Johnny1776 on 25/08/2023.
//

import SwiftUI

extension String {
    /**
     Checks whether the string falls within a specified range and matches a particular pattern.

     - Parameters:
       - range: A closed range defining the minimum and maximum length of the string. Defaults to `2...200`.
       - type: The `StringType` defining the pattern the string must match. Defaults to `.paragraph`.

     - Returns: Returns `true` if the string's length falls within the given range and matches the specified pattern. Returns `false` otherwise.
     */
    func isValid(range: ClosedRange<Int> = 2...200, type: StringType) -> Bool {
        guard range.contains(self.count) else { return false }
        return self.range(of: type.pattern, options: .regularExpression) != nil
    }
}


/**
 Checks whether a given string falls within a specified range and matches a particular pattern.

 This function can be used to validate various string types such as password, username, name, title, age, number, phone number, paragraph, and email.

 - Parameters:
   - range: A closed range defining the minimum and maximum length of the string. Defaults to `2...200`.
   - type: The `StringType` defining the pattern the string must match. Defaults to `.paragraph`.
   - value: The string to be checked.

 - Returns: Returns `true` if the string's length falls within the given range and matches the specified pattern. Returns `false` otherwise.

 - Example Usage:
   - Validate a Password: `checkString(range: 8...16, type: .password, value: "Password123!")`
   - Validate an Email: `checkString(type: .email, value: "john.doe@example.com")`
   - Validate a Phone Number with Custom Length: `checkString(range: 10...15, type: .phoneNumber, value: "123-456-7890")`

 - Note: The patterns for each `StringType` are defined in the `StringType` enumeration. Modify these patterns to suit specific requirements.
 */
func checkString(range: ClosedRange<Int> = 2...200, type: StringType = .paragraph, value: String) -> Bool {
    guard range.contains(value.count) else { return false }
    return value.range(of: type.pattern, options: .regularExpression) != nil
}

enum StringType {
    case password
    case username
    case name
    case title
    case age
    case number
    case phoneNumber
    case paragraph
    case email
    
    var pattern:String {
        switch self {
        case .age:
               return "^[0-9]+$"
           case .name:
               return "^[A-Za-z\\s-']+$"
           case .email:
               return #"^\S+@\S+\.\S+$"#
           case .number:
               return "^[0-9]+$"
           case .paragraph:
               return "^.*$" 
           case .password:
            let passwordPattern =
                // At least 8 characters
                #"(?=.{8,})"# +
                // At least one capital letter
                #"(?=.*[A-Z])"# +
                // At least one lowercase letter
                #"(?=.*[a-z])"# +
                // At least one digit
                #"(?=.*\d)"# +
                // At least one special character
                #"(?=.*[ !$%&?._-])"#
            return passwordPattern
        case .phoneNumber:
               return #"^\(?\d{3}\)?[ -]?\d{3}[ -]?\d{4}$"#
           case .title:
               return "^[A-Za-z0-9\\s.,!?]+$"
           case .username:
               return #"^[a-zA-Z][a-zA-Z0-9_-]*$"#
        }
    }
}