UIToolbar

1. 一般在View的最上面或者最下面，可以加入UIBarButtonItem
2. UIBarItem可以通过storyboard拖拽实现，也可以通过alloc/init方法

UISplitViewController

1. 只能在IPad Storyboard使用
2. 只能作为base UI element

如何使用？

• 默认藏在bar button后面

- (BOOL)splitViewController:(UISplitViewController *)sender
   shouldHideViewController:(UIViewController *)master
              inOrientation:(UIInterfaceOrientation)orientation
{
    return YES; // always hide it 
}

• 永远不藏在bar button 后面

- (BOOL)splitViewController:(UISplitViewController *)sender
   shouldHideViewController:(UIViewController *)master
              inOrientation:(UIInterfaceOrientation)orientation
{
    return NO; // never hide it
 }

• 在portrait模式藏在UIViewController后面

- (BOOL)splitViewController:(UISplitViewController *)sender
   shouldHideViewController:(UIViewController *)master
              inOrientation:(UIInterfaceOrientation)orientation
{
    return UIInterfaceOrientationIsPortrait(orientation);
}

Popover

如何设置popover大小:

• 在viewController里面inspect
• 在content VC controller 里面设置

@property (nonatomic) CGSize contentSizeForViewInPopover;

• 给popover controller发送消息

- (void)setPopoverContentSize:(CGSize)size animated:(BOOL)animated;