Password validation in UITextField in iOS

Question

I have 1 UITextfield for password in my iPhone application.

I want to validate this textfield with the following validation.

• Must be at le

Answer 1

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)

Answer 2

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 3

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 4

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 5

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 6

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;
}