XCode 8: Can't find AFNetworking header files and Swift pods errors

Question

Today I've upgraded my XCode to 8 version, but After this I got a lot of errors. Ex:

The targets “Charts” and “CircleProgressView” contain source code developed with an earlier version of Swift.

Choose “Convert” to update the source code in these targets to the latest SDKs. You will be given the choice to use Swift 2.3 syntax or update to Swift 3.

This action can be performed later using “Convert to Current Swift Syntax” in the Edit menu.

And AFNetworking/AFNetworking.h file not found. The steps I made:

1. Added post_install do |installer| installer.pods_project.targets.each do |target| target.build_configurations.each do |config| config.build_settings['SWIFT_VERSION'] = '2.3' end end end to my Podfile
2. Updated my cocoapods gem to a latest version.

After the 1st step my error about swift module has left. But I still can't find header of my AFNetworking. Help me out please