_tableView.estimatedRowHeight = 50;//预估行高
        _tableView.rowHeight = UITableViewAutomaticDimension;//设置行高自动计算

cell里视图用Masonry做约束

[self.bgImgView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.left.equalTo(self.contentView).offset(10);
        // 提高约束的优先级
        make.size.mas_equalTo(CGSizeMake(100, 100)).priorityHigh();
    }];
    [self.conLabel mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(self.bgImgView.mas_bottom).offset(10);
        make.left.equalTo(self.contentView).offset(10);
        make.bottom.right.equalTo(self.contentView).offset(-10);
    }];