The AdMob iOS SDK is notorious for crashing apps. AdMob has a great fill rate and decent payout, so it’s a shame that the SDK itself is so crummy.
Over the weekend of December 6-7, 2015 I noticed a massive spike in crashes in You Doodle on iOS.
Here is the crash log, clearly pointing to AdMob as the culprit: AdMob crash log.
AdMob recently rolled out interactive ads that let you try apps right in the ad popup. I am 99% sure this is the culprit and I doubt this new ad format was tested adequately.
Thankfully, I have custom server parameters where I can completely disable AdMob, which I have done. If you aren’t already using custom server parameters to enable / disable functions in your apps, I would highly recommend it, at least on iOS. On Android, you can push a new app version out in a matter of minutes or hours so it’s not as critical.
I’ve emailed them and tweeted them about the problem. My guess is it will require an SDK update, which means it will be a few weeks before AdMob makes it back into my apps, given how slow app review is and that they shutdown over Christmas.