Password validation in UITextField in iOS - objective-c

Question

I have 1 UITextfield for password in my iPhone application.
I want to validate this textfield with the following validation.
Must be at least 10 characters
Must contain at least one lower case letter, one upper case letter, one digit and one special character
Valid special characters are – ##$%^&+=^.*(?=.{10,})(?=.*d)(?=.*[a-z])(?=.*[A-Z])(?=.*[##$%^&+=]).*$
How can I restrict the UITextField with above requirements?

Answer 1

This is how I would do it. The validation should be done at the end when the user has typed in the password and not in between.I will not be using NSRegularExpression.
-(void)textFieldDidEndEditing:(UITextField *)textField{
int numberofCharacters = 0;
BOOL lowerCaseLetter,upperCaseLetter,digit,specialCharacter = 0;
if([textField.text length] >= 10)
{
for (int i = 0; i < [textfield.text length]; i++)
{
unichar c = [textfield.text characterAtIndex:i];
if(!lowerCaseLetter)
{
lowerCaseLetter = [[NSCharacterSet lowercaseLetterCharacterSet] characterIsMember:c];
}
if(!upperCaseLetter)
{
upperCaseLetter = [[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:c];
}
if(!digit)
{
digit = [[NSCharacterSet decimalDigitCharacterSet] characterIsMember:c];
}
if(!specialCharacter)
{
specialCharacter = [[NSCharacterSet symbolCharacterSet] characterIsMember:c];
}
}
if(specialCharacter && digit && lowerCaseLetter && upperCaseLetter)
{
//do what u want
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error"
message:#"Please Ensure that you have at least one lower case letter, one upper case letter, one digit and one special character"
delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
}
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error"
message:#"Please Enter at least 10 password"
delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
}
}
Hope this helps...

Answer 2

You can also do this by using Regex. Here are few example I am providing for you:
// *** Validation for Password ***
// "^(?=.*[A-Za-z])(?=.*\\d)[A-Za-z\\d]{8,}$" --> (Minimum 8 characters at least 1 Alphabet and 1 Number)
// "^(?=.*[A-Za-z])(?=.*\\d)(?=.*[$#$!%*#?&])[A-Za-z\\d$#$!%*#?&]{8,16}$" --> (Minimum 8 and Maximum 16 characters at least 1 Alphabet, 1 Number and 1 Special Character)
// "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)[a-zA-Z\\d]{8,}$" --> (Minimum 8 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet and 1 Number)
// "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[$#$!%*?&])[A-Za-z\\d$#$!%*?&]{8,}" --> (Minimum 8 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet, 1 Number and 1 Special Character)
// "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[$#$!%*?&])[A-Za-z\\d$#$!%*?&]{8,10}" --> (Minimum 8 and Maximum 10 characters at least 1 Uppercase Alphabet, 1 Lowercase Alphabet, 1 Number and 1 Special Character)
Fourth from the list is your case, following code snippet shows how to use it:
-(BOOL)isValidPassword:(NSString *)passwordString
{
NSString *stricterFilterString = #"^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[$#$!%*?&])[A-Za-z\\d$#$!%*?&]{10,}";
NSPredicate *passwordTest = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", stricterFilterString];
return [passwordTest evaluateWithObject:passwordString];
}
Using the method:
if(![self isValidPassword:txtPassword.text]) {
/* Show alert: "Password must be minimum 10 characters,
at least 1 Uppercase Alphabet, 1 Lowercase Alphabet,
1 Number and 1 Special Character" */
}
else {
// Password is valid
}

Answer 3

Condition: Password should contain atleast 8 characters, 1 uppercase and 1 number
Solution in Swift 3
you can write String Extension like this,
extension String {
func isValidPassword() -> Bool {
let regularExpression = "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[$#$!%*?&])[A-Za-z\\d$#$!%*?&]{8,}"
let passwordValidation = NSPredicate.init(format: "SELF MATCHES %#", regularExpression)
return passwordValidation.evaluate(with: self)
}
}
//Example 1
var password = "#Abcdef011" //string from UITextField (Password)
password.isValidPassword() // -> true
//Example 2
var password = "Abcdef011" //string from UITextField
password.isValidPassword() // -> false
or you can write function like this,
func validate(password: String) -> Bool
{
let regularExpression = "^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)(?=.*[$#$!%*?&])[A-Za-z\\d$#$!%*?&]{8,}"
let passwordValidation = NSPredicate.init(format: "SELF MATCHES %#", regularExpression)
return passwordValidation.evaluate(with: password)
}
this will give you the same result.

Answer 4

Swift 3
check if password is strong ?
length more than or equal 8
lowercase
uppercase
decimal Digits
special characters like !##$%^&*()_-+ is optional
Why i not use regular expression ?
Because it's difficult to support reserved characters in regular
expression syntax.
func isValidated(_ password: String) -> Bool {
var lowerCaseLetter: Bool = false
var upperCaseLetter: Bool = false
var digit: Bool = false
var specialCharacter: Bool = false
if password.characters.count >= 8 {
for char in password.unicodeScalars {
if !lowerCaseLetter {
lowerCaseLetter = CharacterSet.lowercaseLetters.contains(char)
}
if !upperCaseLetter {
upperCaseLetter = CharacterSet.uppercaseLetters.contains(char)
}
if !digit {
digit = CharacterSet.decimalDigits.contains(char)
}
if !specialCharacter {
specialCharacter = CharacterSet.punctuationCharacters.contains(char)
}
}
if specialCharacter || (digit && lowerCaseLetter && upperCaseLetter) {
//do what u want
return true
}
else {
return false
}
}
return false
}
let isVaildPass:Bool = isValidated("Test**00+-")
print(isVaildPass)

Answer 5

You can verify your password validation using the below function just pass a password string and this will return you BOOL value.
-(BOOL) isPasswordValid:(NSString *)pwd {
NSCharacterSet *upperCaseChars = [NSCharacterSet characterSetWithCharactersInString:#"ABCDEFGHIJKLKMNOPQRSTUVWXYZ"];
NSCharacterSet *lowerCaseChars = [NSCharacterSet characterSetWithCharactersInString:#"abcdefghijklmnopqrstuvwxyz"];
//NSCharacterSet *numbers = [NSCharacterSet characterSetWithCharactersInString:#"0123456789"];
if ( [pwd length]<6 || [pwd length]>20 )
return NO; // too long or too short
NSRange rang;
rang = [pwd rangeOfCharacterFromSet:[NSCharacterSet letterCharacterSet]];
if ( !rang.length )
return NO; // no letter
rang = [pwd rangeOfCharacterFromSet:[NSCharacterSet decimalDigitCharacterSet]];
if ( !rang.length )
return NO; // no number;
rang = [pwd rangeOfCharacterFromSet:upperCaseChars];
if ( !rang.length )
return NO; // no uppercase letter;
rang = [pwd rangeOfCharacterFromSet:lowerCaseChars];
if ( !rang.length )
return NO; // no lowerCase Chars;
return YES;
}

Answer 6

for me Best way was to use NSPredicate and regex.
this is regex for your case: ^(?=.{10,})(?=.*[0-9])(?=.*[a-zA-Z])([##$%^&=a-zA-Z0-9_-]+)$
objective C code:
NSString *regex = #"^(?=.{10,})(?=.*[0-9])(?=.*[a-zA-Z])([##$%^&=a-zA-Z0-9_-]+)$";
NSPredicate *passwordTest = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", regex];
BOOL isValid = [passwordTest evaluateWithObject:yourTextfield.text];

Answer 7

use a regex (NSRegularExpression class has docs on how to write the patten itself) and then :
- (BOOL)textField:(UITextField *)theTextField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
//delete
if (string.length == 0) {
return YES;
}
if (self.regEx) {
NSMutableString* check = [NSMutableString stringWithString:theTextField.text];
[check replaceCharactersInRange:range withString:string];
NSTextCheckingResult* match = [self.regEx firstMatchInString:check options:0 range:NSMakeRange(0, [check length])];
if (match.range.length != check.length) {
return NO;
}
}
}
Warning: Restricting the input this way is really confusing for users. You type and type and the character you type just doesnt appear!
I'd maybe go with a small red (!) next to the test field but I'd always allow the input itself!

Answer 8

I have this elegant solution for Forms (like sign-up) where you have a lot of validation
I have in my custom UITextField the outlet:
#IBInspectable var regexpValidation: String? = nil
In storyboard I can access it through attribute inspector and put regexp string like that (for email):
[a-z0-9!#$%&'*+/=?^_{|}~-]+(?:.[a-z0-9!#$%&'*+/=?^_{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?
then in my subclass I have this computed var:
#IBInspectable var regexpValidation: String? = nil // Optional, Set this in InterfaceBuilder
var inputIsValid: Bool {
get {
if let expr = regexpValidation {
return (text.rangeOfString(expr, options: NSStringCompareOptions.RegularExpressionSearch, range: nil, locale: nil) != nil)
} else {
return true
}
}
}
which could be used like this:
override func resignFirstResponder() -> Bool {
if (inputIsValid) {
return super.resignFirstResponder()
}
else {
text = ""
return false
}
}

Answer 9

You need to write your validation code in this delegate method of UITextField
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
Few links that you might want to refer for implementation
how to use regular expression in iOS sdk
iOS TextField Validation

Answer 10

Use the control:isValidObject: method of the NSTextFieldDelegate protocol which allows you to validate the value of a NSTextField. Assuming you have all your interface builder bits and pieces configured correctly, you might do something like this:
#interface PreferencesController : NSWindowController <NSTextFieldDelegate> {
IBOutlet NSTextField *username, *password;
}
#end
#implementation PreferencesController
- (BOOL)control:(NSControl *)control isValidObject:(id)object
{
if (control == password) {
// Perform validation and return YES or NO
}
return YES;
}
#end

Answer 11

SWIFT 5 USING RXSWIFT, a better, neat and reactive approach.
validate password function will be like this, Obviously you can add as many conditions as you want as per your requirement.
func validatePassword(password: String) -> (Bool, String) {
//Minimum 8 characters at least 1 Alphabet and 1 Number:
var tuple: (Bool, String) = (true, "")
var string = "Requires atleast"
if(password.rangeOfCharacter(from: CharacterSet.letters) == nil){
string = "uppercase"
tuple = (false, string)
}
if(password.rangeOfCharacter(from: CharacterSet.decimalDigits) == nil){
string += ", number"
tuple = (false, string)
}
if(password.count < 8 ){
string += ", 8 chars"
tuple = (false, string)
}
return tuple }
func isPasswordValid(in string: String) -> Observable<(Bool, String)> {
return Observable.create { observer -> Disposable in
let tuple = self.validation.validatePasswordForSymbol(password: string)
observer.onNext(tuple)
return Disposables.create()
}
}
You can use aforementioned function in viewModel or VC as per your architecture.
Then invoke the same function like below in your VC.
passwordTextField.rx.text
.orEmpty //1
.filter { $0.count >= 1 } //2
.flatMap { self.isPasswordValid(in: $0) }
.subscribe(onNext: { result in
print("Valid password", result)
//update UI here
// result will be like (false, "Requires atleast, 8 chars, number")
}).disposed(by: disposeBag)