It’s every app developers dream time when he develops and then uploads his app to Apple App Store using Xcode.
At that moment of time while uploading your app if you are stuck in one place where Xcode organiser says “Uploading to App Store – Authenticating with iTunes Store” & there is no further progress.
Then here is how to solve this!
Just open Terminal App from your Applications > Utilities > Terminal.
Paste below code in Terminal & hit return key.