The issue is because of Apple WWDRCA expired at Feb 14, 2016.

to resolve this

• go to your Keychain Access, and in the menu

• click View - - > Show Expired Certificates.

delete the expired Apple Worldwide Developer Relations Certificate Authority from both the login and System Keychains.

• under System you can see like your certificate is expired

• Install the renewed certificate from Apple by downloading and double click it.

• restart your xcode

• Clean your project and Build