example cell height from AF

+ (CGFloat)heightForCellWithPost:(Post *)post {
    return (CGFloat)fmaxf(70.0f, (float)[self detailTextHeight:post.text] + 45.0f);
}

+ (CGFloat)detailTextHeight:(NSString *)text {
    CGRect rectToFit = [text boundingRectWithSize:CGSizeMake(240.0f, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:12.0f]} context:nil];
    return rectToFit.size.height;
}