纯代码TableView自适应高度（很老的使用方法）

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return self.arr.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
cell.textLabel.numberOfLines = 100;
cell.textLabel.font = [UIFont systemFontOfSize:15];
cell.textLabel.text = self.arr[indexPath.row];
return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{

NSString* text = self.arr[indexPath.row];

CGSize constraint = CGSizeMake(375-40, 100);

NSAttributedString* attributedText = [[NSAttributedString alloc]initWithString:text attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:15]}];

CGRect rect = [attributedText boundingRectWithSize:constraint options:NSStringDrawingUsesLineFragmentOrigin context:nil];

CGSize size = rect.size;

CGFloat height = MAX(size.height, 20);
NSLog(@"%f",height);
return height+10;

}