Google Mobile Ads issue in iPhone 6

If you get when trying to enable http mode on IOS platform like this: 

App Transport Security has blocked a cleartext HTTP (http://) resource load since it is insecure. Temporary exceptions can be configured via your app's Info.plist file.

interstitial didFailToReceiveAdWithError: Error Code=13 "Request Error: Received invalid response." UserInfo={NSLocalizedDescription=Request Error: Received invalid response., NSLocalizedFailureReason=Request Error: Received invalid response.}

Failed to receive ad with error: Request Error: Received invalid response.

you have to set the NSAllowsArbitraryLoads key to YES under NSAppTransportSecurity dictionary in your .plist file.