Q: Can't get MoPub set up with fabric.io 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!"
Any hints?

A: 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
Fabric.with([Twitter.self])

in a submodule init(). This collided with the statement
Fabric.with([Twitter.self, MoPub.self])

which is located in AppDelegate. After deleting the first (Twitter-only) initialization statement, everything now works.

A: Similar problem here but an entirely different issue. Fabric uses temp files and I had a procedure near the start of the app which was manually clearing the temp directory, causing a race condition with the Fabric initialisation.
The solution of course was to move the Fabric initialisation after the temp cleardown.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
   // Do any manual cleaning of NSTempDirectory() and NSCachesDirectory() here

   [Fabric with:@[[Crashlytics class], [MoPub class]]];
   ...

