iPad App里涉及到弹出窗口，经常会用到UIPopoverController。UIPopoverController的使用比较简单。
1、初始化：
- (id)initWithContentViewController:(UIViewController *)viewController;
通过contentVC来初始化popover
示例：
TXContentViewController * contentVC = [[TXContentViewController alloc]initWithNibName:nil bundle:nil];
self.popoverVCA = [[UIPopoverController alloc]initWithContentViewController:contentVC];
2、弹出popover
系统提供了2种方法：
- (void)presentPopoverFromRect:(CGRect)rect inView:(UIView *)view permittedArrowDirections:(UIPopoverArrowDirection)arrowDirections animated:(BOOL)animated;
通过指定一块区域弹出popover
- (void)presentPopoverFromBarButtonItem:(UIBarButtonItem *)item permittedArrowDirections:(UIPopoverArrowDirection)arrowDirections animated:(BOOL)animated;
通过一个barButtonItem弹出popover
示例：
[self.popoverVCA presentPopoverFromRect:CGRectMake(200, 200, 100, 100) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES] ;
demo示意图：
重要概念：
1、popover的箭头方向
skd的文档里定义如下：
typedef NS_OPTIONS(NSUInteger, UIPopoverArrowDirection) {
UIPopoverArrowDirectionUp = 1UL << 0, //向上
UIPopoverArrowDirectionDown = 1UL << 1, //向下
UIPopoverArrowDirectionLeft = 1UL << 2, //向左
UIPopoverArrowDirectionRight = 1UL << 3, //向右
UIPopoverArrowDirectionAny = UIPopoverArrowDirectionUp | UIPopoverArrowDirectionDown | UIPopoverArrowDirectionLeft | UIPopoverArrowDirectionRight, //上下左右
UIPopoverArrowDirectionUnknown = NSUIntegerMax
};
2、相关属性
@property (nonatomic, retain) UIViewController *contentViewController;
@property (nonatomic, readonly, getter=isPopoverVisible) BOOL popoverVisible;
@property (nonatomic, readonly) UIPopoverArrowDirection popoverArrowDirection;
@property (nonatomic, copy) UIColor *backgroundColor NS_AVAILABLE_IOS(7_0);
demo源码见：https://github.com/tingxuan/TXUIPopoverDemo