iOSでポップアップビューの自作を行う。 ref: http://qiita.com/g-1/items/bbf785e32bdfb66eb714

PopupViewController.m

- (IBAction)close:(id)sender
{
  [UIView animateWithDuration:0.2f
                   animations:^{
                     self.view.alpha = 0.2f;
                   }
                   completion:^(BOOL finished){
                     [self.view removeFromSuperview];
                     self.view.alpha = 1.f;
                   }];
}

ViewController.m

- (IBAction)popup:(id)sender
{
  [self.view addSubview:self.popupViewController.view];

  CGPoint center = self.popupViewController.contentView.center;

  UIView* view = self.popupViewController.contentView;

  view.transform = CGAffineTransformScale(CGAffineTransformIdentity,0.5f,0.5f);
  view.center = center;

  [UIView animateWithDuration:0.2
                        delay:0.0
                      options:UIViewAnimationOptionCurveEaseInOut
                   animations:^{
                     view.transform = CGAffineTransformIdentity;
                     view.center = center;
                   }
                   completion:nil];

}