ios 12 中的新特性。 已经有很多文章写得很好,这里不再赘述,直接给大家几个传送门:
https://sspai.com/post/47168
https://post.smzdm.com/p/771705/
https://www.jianshu.com/p/dde4fef41c4b
https://www.jianshu.com/p/8b49fc037a89
http://www.cocoachina.com/ios/20180926/25026.html
https://baijiahao.baidu.com/s?id=1611958169330021624&wfr=spider&for=pc
https://www.jianshu.com/p/b93753843a67