UIActionSheet 箭头方向

1.调整ipad上UIActionSheet的arrow方向
ipad上面UIActionSheet可以有箭头，但其方向不能像popover那样调整，上面查资料有如下解决方法：
参考：http://stackoverflow.com/questions/3763324/uiactionsheet-change-arrow-position

重要的就是这两句：
Apple doesn't provIDe any access to internal structure for UIActionSheet's internal implementation of showFromrect,but as for arrow direction,there is actually a very Hack-y way to work around this and sort of being able to change arrow direction to a desired direction.
Trick is to mess around the rect parameter in - (voID)showFromrect:(CGRect)rect inVIEw (UIVIEw *)vIEw animated:(BOol)animated. Apple doesn't document this rect parameter very well,butif your original rect will give you a down arrow direction,Feed in a rect with a large height and negative number origin.y will kind of push the action sheet popover all the way up thus showing a upward arrow direction. This is a extreme Hack but it works consistently across firmware. 

2.应用
工作中遇到编辑头像，图片来源：camera,album两种，在Iphone上面没有问题，但在Ipad上由于上面区别就有问题了
先dUIActionSheet,但d出来的总是箭头向下的，我想d个箭头向上，以便切换成Popover时在同一位置

初始代码：

UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:nil delegate:self cancelbuttonTitle:nil destructivebuttonTitle:@"camera" otherbuttonTitles:nil];    [sheet addbuttonWithTitle:@"album"];    // avaterBtn bounds:(0,80,80)    [sheet showFromrect:CGRectMake(0,80) inVIEw:avaterBtn animated:YES];    [sheet release];

UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:nil delegate:self cancelbuttonTitle:nil destructivebuttonTitle:@"camera" otherbuttonTitles:nil];    [sheet addbuttonWithTitle:@"album"];    [sheet showFromrect:CGRectMake(0,-200,280) inVIEw:avaterBtn animated:YES];    [sheet release];