ios如何在navigation上添加多个按钮

UIBarButtonItem *cleanButton = [[UIBarButtonItem alloc] initWithTitle:@"清空"
                                                                        style:UIBarButtonItemStylePlain  
                                                                       target:self       
                                                                       action:@selector(cleanTextView)];
        UIBarButtonItem *saveButton = [[UIBarButtonItem alloc] initWithTitle:@"保存"
                                                                       style:UIBarButtonItemStylePlain  
                                                                      target:self       
                                                                      action:@selector(saveTextView)];
        NSArray *buttonArray = [[NSArray alloc]initWithObjects:cleanButton,saveButton, nil];
        self.navigationItem.rightBarButtonItems = buttonArray;