Check a string for a whitespace by creating an NSArray from an NSString separated by a whitespace. If this count is greater than one, then there is at least 1 whitespace.

Check for white-spaces in iOS

NSArray *checkPasswordForWhitespace = [password.text componentsSeparatedByString:@" "];
    
    NSLog(@"%@", checkPasswordForWhitespace);
    
    if ([checkPasswordForWhitespace count] > 1) {
        
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Whitespace" message:@"Please remove the whitespace from your password." delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
        [alert show];
        
        return;
        
    }