Enter date format from keyboard in dd/mm/yyyy format -----> IOS

NSMutableString *filteredPhoneStringFromStringWithFilter(NSString *string, NSString *filter)

{

    NSUInteger onOriginal = 0, onFilter = 0, onOutput = 0;

    char outputString[([filter length])];

    BOOL done = NO;

    

    while(onFilter < [filter length] && !done)

    {

        char filterChar = [filter characterAtIndex:onFilter];

        char originalChar = onOriginal >= string.length ? '\0' : [string characterAtIndex:onOriginal];

        switch (filterChar) {

            case '#':

                if(originalChar=='\0')

                {

                    // We have no more input numbers for the filter.  We're done.

                    done = YES;

                    break;

                }

                if(isdigit(originalChar))

                {

                    outputString[onOutput] = originalChar;

                    onOriginal++;

                    onFilter++;

                    onOutput++;

                }

                else

                {

                    onOriginal++;

                }

                break;

            default:

                // Any other character will automatically be inserted for the user as they type (spaces, - etc..) or deleted as they delete if there are more numbers to come.

                outputString[onOutput] = filterChar;

                onOutput++;

                onFilter++;

                if(originalChar == filterChar)

                    onOriginal++;

                break;

        }

    }

    outputString[onOutput] = '\0'; // Cap the output string

    return [NSMutableString stringWithUTF8String:outputString];

}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    

    NSString *filter = @"##/##/####";

    if(!filter) return YES; // No filter provided, allow anything

    

    NSString *changedString = [textField.text stringByReplacingCharactersInRange:range withString:string];

    

    if(range.length == 1 && // Only do for single deletes

       string.length < range.length &&

       [[textField.text substringWithRange:range] rangeOfCharacterFromSet:[NSCharacterSet characterSetWithCharactersInString:@"0123456789"]].location == NSNotFound)

    {

        // Something was deleted.  Delete past the previous number

        NSInteger location = changedString.length-1;

        if(location > 0)

        {

            for(; location > 0; location--)

            {

                if(isdigit([changedString characterAtIndex:location]))

                {

                    break;

                }

            }

            changedString = [changedString substringToIndex:location];

        }

    }

    

    textField.text = filteredPhoneStringFromStringWithFilter(changedString, filter);

    

    return NO;

}