I've had a long struggle with this, too, while I was building a private Swift-Framework-Pod that depends on RestKit. After a long fight, I forked RestKit and hacked a workaround.
The drawbacks are, you have to use Cocoapods 0.39, which is pretty legacy
and the hacked version of RestKit is forked of 0.25.0, so it's also not the newest of the new.
To use the fork, in your Podfile, replace
pod 'RestKit', ...
with
pod 'RestKit', :git => 'https://github.com/resmio/RestKit', :tag => 'v0.25.0-use-frameworks'
Also, you might need to use a hacked version of AFNetworking, which also made some problems.
Same here, replace
pod 'AFNetworking', ...
with
pod 'AFNetworking', :git => 'https://github.com/resmio/AFNetworking', :tag => 'v1.3.4-use-frameworks'
I'd be glad if you'd let me know if that wrked for you and if so, spread the word! :)