Some useful regex(Regular Expression) utilities (iOS)

A regex ( also known as regular expressions) is a pattern string. These pattern strings allow you to search specific patterns in documents and to validate email, phone number etc. In iOS and MacOS regex been handled by NSRegularExpression .To know more about NSRegularExpression read apple documentation.

Some Basic Utility Regex

Email verification regex, common email notion xxxx@xxx.xx equivalent regex

[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}

Example:

func validateEmail(testStr:String) -> Bool {

    let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.
                      [A-Za-z]{2,4}" //same as Obj-C

    let emailTest = NSPredicate(format:"SELF MATCHES %@",
                                 emailRegex)
    return emailTest.evaluate(with: testStr)
}

Valid Password Regex

1. 8 characters total
2. at least one lowercase
3. at least one digit
4. at least one uppercase

(?=.*[A-Z])(?=.*[0-9])(?=.*[a-z]).{8,}

Example:

func validatePassword(testStr:String) -> Bool {

    let passwordRegex = "(?=.*[A-Z])(?=.*[0-9])(?=.*[a-z]).{8,}" //same as Obj-C

    let passwordTest = NSPredicate(format:"SELF MATCHES %@",
                                 passwordRegex)
    return passwordTest.evaluate(with: testStr)
}