YYLabel计算富文本高度-膜拜大神

http://www.jianshu.com/p/07cd655fee7e

YYTextLayout *layout = [YYTextLayout layoutWithContainerSize:CGSizeMake(SCREEN_WIDTH - commentLeftMargin * 2, CGFLOAT_MAX) text:self.showingAttribute];
        _commentHeight = layout.textBoundingSize.height;
        NSLog(@"YY计算-%f",_commentHeight);