IOS 3.0之后，navigation controller内置toolbar

表明toolbar及其toolbar基本上的设定编码以下：

[self.navigationController setToolbarHidden:NO animated:NO];

self.navigationController.toolbar.barStyle = UIBarStyleBlack;

UIBarButtonItem *item = [[UIBarButtonItem alloc] initWithBarButtonSystemItem: UIBarButtonSystemItemCompose target:self action:@selector(settingButtonClicked)];

NSArray *myToolbarItems = [[NSArray alloc] initWithObjects: item, nil];

[self setToolbarItems: myToolbarItems animated:YES];

toolbar的掩藏：

NewOrderViewController *newOrder = [[NewOrderViewController alloc] initWithNibName:@"NewOrderView" bundle:[NSBundle mainBundle]];

newOrder.hidesBottomBarWhenPushed = YES;

[self.navigationController pushViewController:newOrder animated:YES];