I have AGOL subscription and an arcgis server account (10.3.1).
I made a webmap that contains a feature service from my server (sql 2008) and I want to add features using the collector app.
On android platform there is no problem. But on ios - when I open the map the app crashes.
I made the map public, it is called: Collector Checking by deshegis.
Sorry for the very late reply on this. Just retested your map (thanks for sharing!) with the latest version on iOS (18.0.1) and was able to open and work as expected.