初始化cell 的2种方法

DiscoverJokeCell *cell = [tableView dequeueReusableCellWithIdentifier:cellJokeIdentify forIndexPath:indexPath];//            DiscoverJokeCell *cell = (DiscoverJokeCell *)[tableView dequeueReusableCellWithIdentifier:cellJokeIdentify];//            if (!cell) {//                cell = [[[NSBundle mainBundle] loadNibNamed:@"DiscoverJokeCell" owner:self options:nil] objectAtIndex:0];//            }