是否可以在导航栏的左侧放置两个按钮，并转换OnClick上最左侧的按钮？

如果只想添加简单的UIButton，则可以使用以下方法。

1）创建多个UIButton对象

2）将所有这些按钮添加到UIView对象

3）创建UIBarButtonItem并将UIView作为自定义视图传递

代码如下：

// create the container view
UIView* viewContainer = [[UIView alloc] init];

// Create buttons and add it to the container view
UIButton* btnAdd = [UIButton buttonWithType:UIButtonTypeRoundedRect];

[btnAdd setTitle:@"Add" forState:UIControlStateNormal];
[viewContainer addSubview:btnAdd];

UIButton* btnRefresh = [UIButton buttonWithType:UIButtonTypeRoundedRect];

[btnRefresh setTitle:@"Refresh" forState:UIControlStateNormal];
[viewContainer addSubview:btnRefresh];

// now create a Bar button item with custom view
UIBarButtonItem* barBtnItem = [[UIBarButtonItem alloc] initWithCustomView:viewContainer];

// Set the navigation bar's right button item
self.navigationItem.rightBarButtonItem = barBtnItem;

否则，如果您想添加BarUIBarButtonItems，则可以添加多个barbutton，如Anbu.Karthik所说。

这是添加多个条形按钮项目的代码。

// Create UIToolbar to add two buttons in the right
UIToolbar* toolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 133, 44.01)];

// Create standard "add" button
UIBarButtonItem* btnAdd = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:NULL];
btnAdd.style = UIBarButtonItemStyleBordered;

// Create spacer
UIBarButtonItem* spacer = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];

// create standard "refresh" button
UIBarButtonItem* btnRefresh = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(btnRefresh_Clicked:)];
btnRefresh.style = UIBarButtonItemStyleBordered;

// stick the buttons in the UIToolbar
[toolBar setItems:@[btnAdd, spacer, btnRefresh] animated:NO];

// Put the toolbar in the UINavigationBar
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:toolBar];

希望这会帮助你。:)