If anyone is having problems with RestKit 0.26.0 and Cocoapods 1.0.1 in a Swift project using Xcode 7.3, hope this helps!
This solution worked, at least in 2016-06-03, but since it uses certain git branches, they may be merged, so if this does not work for you, check if these git branches have been merged / moved / deleted .
Clear in front of everyone
Quit Xcode
rm -rf Pods
rm -rf MyApp.xcworkspace
rm -rf ~/Library/Caches/CocoaPods
rm -rf ~/Library/Developer/Xcode/DerivedData
"" AFNetworking
pod 'AFNetworking', :git => 'https://github.com/mcfedr/AFNetworking.git', :branch => 'reachability'
pod 'RestKit', :git => 'https://github.com/mcfedr/RestKit.git', :branch => 'pods1'
@import RestKit;
!