Archive Button grayed out.

Remember, you can't archive if:

- a simulator is selected instead of a device*

- there is an error when building*

- you haven't finished the 'Prepare for Submission’ stage for that app in iTunes Connect

- See: https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/ChangingAppStatus.html

- you've recently renewed your (required) apple developer account, and not yet updated the provisions to reflect that activity

* You must have at least one device registered in the Member Center, but it doesn’t have to be connected to your Mac/Xcode when building, in which case select ‘generic iOS/tvOS device'

- - - If this is just about testing to a device and you're getting a message that Xcode can't archive, try deleting all older versions of that app on the target device first

Also see TN2215: Why is the Archive menu item grayed out in Xcode ?

Finally found an answer for this, Thanks to Stackoverflow user who wrote an answer this.

Kindly find detailed steps given here -> http://knowledge-cess.com/reactnative-0-59-8-project-unable-to-archive-for-for-ios-while-app-store-release-validate-buttons-is-always-grayed-out/