At this point I think that a lot of the Apple dev community would be happy with clear documentation on using Xcode with SPM. They would be thrilled with iOS support, let alone some sort of IDE support.
We are a macOS dev shop and are about to try using SPM to maintain modules and build a shipping project out of them. If successful I'm going to write it up as well. We currently use Carthage for maintaining some of our internal dependencies, but then everyone, including build servers, needs to install and configure Carthage. SPM is built-in which is one of the primary draws it has for me.
The thing that trips Xcode up more than anything seems to be the fact that SPM isn't just a package manager, it also is the build chain and testing rig. This means you need to do things like add a
swift build script step to the Xcode build process and then you end up duplicating lots of work. All I really want is a way to just easily compose macOS apps from separate modules that we create and maintain internally.
Testing is more of the same. I love that I can test non-exectuable bundles and modules with it, but I also wish that testing integrated well into Xcode. I can write my tests in the test editor in Xcode, but then I need to drop out to the terminal to test them and I don't get code coverage. I can deal with this, but it's annoying.
I think some of the posts you see these days are the result of Xcode/SPM frustration. After three years in the world it feels like the SPM teams don't care about Xcode users. To be clear I know that's not the case. If it were, things like these forum threads wouldn't exist! This year at WWDC the people sitting on either side of me walked out of the SPM session because it didn't cover iOS or Xcode.
I know that SPM aims to be IDE and platform agnostic, but I also know that the majority of the Swift user base are developers with Apple tools, on Apple platforms, for Apple platforms. I also realize that the Xcode issue isn't for the SPM team to solve, it's in Xcode's court. (Yes, I've filed radars on Xcode but I was internal at the time and no longer have the numbers as that developer account is dead.)
If this comes off as a rant I don't mean it to. The Apple developer community is just so close now to having really great ways to compose and maintain Apps.