Im planning to add a text within an app stating what RestKit version the app is currently using. So I wonder if there is an easy way to get the current version number of the RestKit installed via CocoaPods.
...Or, is there a way to check the version of the staticlib libPods-RestKit.a?
No, there isn't. The version number is held in a file in the project but this file isn't built into the library and there is no API provided to get the version number. There is no standard method for providing version numbers in static libraries so this isn't a frequent requirement.
Anything you do would be an explicit solution on your part. Your best option would likely be to fork the RestKit repo and make some small changes or to reference the VERSION file from the RestKit project in your main project so it's copied into the app and you can read it from disk at runtime...