Xcode 7.3, iOS9.3.3
Following the instructions above, but wanted to expand, hoping to save time. If you already have the Google-Mobile-Ads-SDK installed, check the version to make sure it is 7.9.0 + . Otherwise, you will continue to install the old version again and again.
To upgrade, follow the instructions on the Cocoapods website https://cocoapods.org/pods/Google-Mobile-Ads-SDK click on the “Installation Guide” (bottom right):

The bit '~> 7.9' will force the update.
What I did not succeed:

What it should be:

Note again that version 7.9.1
The subfile is as follows:
Now you can configure GADMobileAds using the method prescribed by Google:
[GADMobileAds configureWithApplicationID:@""];
Or the Swift equivalent:
GADMobileAds.configureWithApplicationID("");
Hope this helps! Greetings.
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