我希望滚动后的效果如图1，实际效果却是图2.代码在下面，求助。

-(void)scrollToBottom
{

unsigned long count = self.frameModelArray.count;
if (count>0) {
    NSIndexPath *lastIndex = [NSIndexPath indexPathForRow:count-1 inSection:0];
    [self.tableView scrollToRowAtIndexPath:lastIndex atScrollPosition:UITableViewScrollPositionBottom animated:YES];
    [self.view layoutIfNeeded];
}

}