UITableView快速回到顶部有三种方法:
(1)[self.tableView scrollRectToVisible:CGRectMake(0, 0, 1, 1) animated:NO];
(2)[self.tableView setContentOffset:CGPointMake(0,0) animated:NO];
(3)NSIndexPath* indexPat = [NSIndexPath indexPathForRow:0 inSection:0];
[self.tableView scrollToRowAtIndexPath:indexPat atScrollPosition:UITableViewScrollPositionBottom animated:YES];