Keychain and Xcode

To add Keychain access group to your app you have to enable entitlements for this app in Xcode and add access group there. When you enable entitlements, Xcode automatically adds your bundle identifier to access group list. That's enough to use this string as shared access group in your app, right? WRONG. You get all kinds of error messages when trying to use shared access group, then open entitlements file and find that that access group is only displayed as nice and clean com.yourcompany.yourapp, and actually is $(AppIdentifierPrefix).com.yourcompany.yourapp. And when you remove this prefix, shared access group works all right. And after device&Xcode restart shared access groups without AppidentifierPrefix stop working, and start working with it.