动态计算UITableViewCell高度<进阶>

@property (nonatomic, strong) UITableViewCell *prototypeCell;

//注册Nib
UINib *cellNib = [UINib nibWithNibName:@"NLGC" bundle:nil];
[self.tableView registerNib:cellNib forCellReuseIdentifier:@"NLGC"];
self.prototypeCell  = [self.tableView dequeueReusableCellWithIdentifier:@"NLGC"];

//CellForIndexPath
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NLGC *cell = [self.tableView dequeueReusableCellWithIdentifier:@"NLGC"];
    cell.t.text = [self.tableData objectAtIndex:indexPath.row];
    return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath 
{
    NLGC *cell = (NLGC *)self.prototypeCell;
    cell.t.text = [self.tableData objectAtIndex:indexPath.row];
    CGSize size = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize];
    NSLog(@"h=%f", size.height + 1);
    return 1  + size.height;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    C3 *cell = [self.tableView dequeueReusableCellWithIdentifier:@"C3"];
    cell.t.text = [self.tableData objectAtIndex:indexPath.row];
    [cell.t sizeToFit];
    return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    C3 *cell = (C3 *)self.prototypeCell;
    NSString *str = [self.tableData objectAtIndex:indexPath.row];
    cell.t.text = str;
    CGSize s = [str calculateSize:CGSizeMake(cell.t.frame.size.width, FLT_MAX) font:cell.t.font];
    CGFloat defaultHeight = cell.contentView.frame.size.height;
    CGFloat height = s.height > defaultHeight ? s.height : defaultHeight;
    NSLog(@"h=%f", height);
    return 1  + height;
}

- (CGSize)calculateSize:(CGSize)size font:(UIFont *)font 
{
    CGSize expectedLabelSize = CGSizeZero;

    if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7) {
        NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
        paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
        NSDictionary *attributes = @{NSFontAttributeName:font, NSParagraphStyleAttributeName:paragraphStyle.copy};

        expectedLabelSize = [self boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;
    }
    else {
        expectedLabelSize = [self sizeWithFont:font
                                       constrainedToSize:size
                                           lineBreakMode:NSLineBreakByWordWrapping];
    }

    return CGSizeMake(ceil(expectedLabelSize.width), ceil(expectedLabelSize.height));
}