Error "library not found for" after putting application in AdMob
Sometimes you just remove the reference of the library and add reference again.
Apart from adding the Google Mobile Ads SDK and other libraries again from scratch, I would recommend you checking the Library Search Paths. There are instances when you copy or duplicate a target, Xcode decides that it needs to escape any double quotes " with a '\'. Make sure you remove all the \’s - it should look like this -
I was able to duplicate the error, by doing prefixing my path with multiple '\'.