I got 404 error in most of the link in Arcgis run-time-sdk for iOS. The below mensioned url is an example.
I'm sorry you're experiencing this issue. This particular community is about ArcGIS Hub, so unfortunately we aren't going to be able to solve this issue, but I wanted to let you know that I have reported it to someone who is going to try to find the right folks who can fix this.
For issues related to the Runtime SDk for iOS you can report issues here https://community.esri.com/t5/arcgis-runtime-sdk-for-ios/bd-p/arcgis-runtime-sdk-for-ios-questions and someone from that team can provide help and act on issues. thanks for reporting this we will look into it.