IOS 12 issue - API connections (inc. workaround)

Since updating to IOS 12 I have been having some issues with a web project that connects to data via API. All was working well on desktop until I tried the site on my iPhone and the data wouldn’t load.

In the dev console the preflight checks were failing but CORS was correctly set up and working on the API (as proven by it working on desktop).

After some research it appears that there is a bug in IOS 12 blocking the OPTIONS request and subsequently causing CORS to fail. There are some reports, that I have not tested yet, that the latest beta resolves the issue.

I just wanted to share this to hopefully save others, who hitting the same brick wall as me, wasting valuable time.