#pragma mark -- TextField代理

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

/*

 // Method - one

    int limit = 3;

    return !([textField.text length] > limit && [string length] > range.length);

*/

 // Method - two

    if (textField == self.passWordLabel) {

        if (range.length + range.location > textField.text.length) {

            return NO;

        }

        NSUInteger newLength = [textField.text length] + [string length] - range.length;

        return newLength <= ;

    }

    return YES;

}