Sorry, but all along iphone camera are not strong. You don't buy a iphone just because you want to take good photos. It's the overall experience of using iphone. Until now, even my oppo X8 is still not as good in SW when compared to my 17pm. You don't need to wait until X300pro or X9pro to release to tell you iphone camera are not strong.
iphone camera does its job well. It's not as sucky as you think. Of cos when compared to X9pro and X300pro it's not as good but taking good photo doesn't mean you need to have a very good phone. The one triggering that button is more important.
There is a iphone photography thread here, you can take a look.
https://forums.hardwarezone.com.sg/threads/post-pictures-taken-by-your-iphone.5468024/