- (IBAction)showSheet:(id)sender {
UIActionSheet *actionSheet = [[UIActionSheet alloc]
initWithTitle:@"title,nil时不显示"
delegate:self
cancelButtonTitle:@"取消"
destructiveButtonTitle:@"确定"
otherButtonTitles:@"第一项", @"第二项",nil];
actionSheet.actionSheetStyle = UIActionSheetStyleBlackOpaque;
[actionSheet showInView:self.view];
}