继承UIPopoverController，实现在popover在dismiss时自动调用代理方法，默认情况下通过dismissPopoverAnimated:方法来清除popover时，不会调用代理的方法。

MMPopoverController.h

//
//  MMPopoverController.h
//  Animation
//
//  Created by manjun.han on 04/06/2013.
//  Copyright (c) 2013 animation. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface MMPopoverController : UIPopoverController

@end

MMPopoverController.m

//
//  MMPopoverController.m
//  Animation
//
//  Created by manjun.han on 04/06/2013.
//  Copyright (c) 2013 animation. All rights reserved.
//

#import "MMPopoverController.h"

@implementation MMPopoverController

- (void)dismissPopoverAnimated:(BOOL)animated
{
    if ([self.delegate respondsToSelector:@selector(popoverControllerShouldDismissPopover:)]) {
        if (![self.delegate popoverControllerShouldDismissPopover:self]) {
            return ;
        }
    }
    
    [super dismissPopoverAnimated:animated];
    
    if ([self.delegate respondsToSelector:@selector(popoverControllerDidDismissPopover:)]) {
        [self.delegate popoverControllerDidDismissPopover:self];
    }
}

@end