MyClass is unavailable: cannot find Swift declaration for this class - Release Build Only
If MyClass is inside a dynamic framework (Cocoa Touch Framework), It is likely that you're using a build with wrong architecture. To check, browse your MyClass.framework in finder, and check Modules/AirServiceKit.swiftmodule. There should be something like x86_64.swiftmodule or arm64.swiftmodule, if you're using simulator there should be x86, or arm if you're building for device.
In case anyone else encounter this problem:
I had the exact same error and turned out that I had built my framework for an specific emulator. I changed the device (in upper left corner) to Generic iOS device and did a clean and build, then I used the generated .framework file.
Everything worked just fine after using this generated .framework file.
In my case, it was because my framework that I am developing was missing one of the Valid Architectures listed in my app's target. All I had to do was the following:
- Go to Project file.
- Go to Build Settings for the app target you're trying to build. Note the architectures listed under Valid Architectures.
- Go to the framework target that is failing.
- Make sure all the architectures match.
In my case, my framework was missing arm64.