By the look of the errors it seems the Swift syntax of starscream is not using Swift 2. This is hinted by the error on 'join' (Swift1.0 syntax) whereas joinWithSeparator() is Swift 2 syntax).

In Podfile[1] check you're pointing to starscream 1.0.2+ or latest version on master. Previous version of the lib used Swift 1 syntax.

++

Corinne

[1] https://github.com/aerogear/aerogear-ios-sync-client/blob/master/Podfile#L8