Using fabric.io, I included the MoPub package into my iOS App and set up my UI with a banner and an interstitial ad. Everything builds fine without any warnings, and the app does show the test ads in both variants.
But the Fabric application in OS X does not recognize my app running. It gets notified about the successful build, but in the next step "Verifying Installation…", after a while it says "Hmmm, seems like your kit isn't activating". Note that I am using a real iPhone device, no simulator.
Also, the fabric.io portal says "Include the MoPub Kit from your plugin to get started!"
So, the solution was rather simple: Prior to MoPub I already had included the Twitter package of fabric.io (TwitterKit). Therefore I had the sequence
in a submodule
init(). This collided with the statement
which is located in
AppDelegate. After deleting the first (Twitter-only) initialization statement, everything now works.