How to resize bubble after set dynamaic text font

[web8246]

hi there: I want to chang text font size dynamically, if I set textview font to preferredFont ,it works well, however, according to ios11, if I set UIFontMetrics to give uitextview text font a specific size ,the font size did changed ,but bubble size not changed to what I expected, any suggesstion would be helpful.

[zhuozhuo]

Hi Web,
This font is displayed, but the height error, I think it should be because of the high cache, you put the height of the cache to remove the first try. If it's convenient, you can give me a demo address.