[Solved] Upgrade Xcode 7.3.1 Project to Xcode 8.0

The final answer of above question is:

add the code snippet in your podfile

   post_install do |installer|
    installer.pods_project.targets.each do |target|
      target.build_configurations.each do |config|
        config.build_settings['SWIFT_VERSION'] = '3.0'

then check swift legacy in build settings
and set it to NO for swift 3 or you can
set Yes for swift 2.3 (if you are using objective-c pod repository)

Check all the pod repository one by one if its update contain swift3 code then fine or you can manually add code with swift 3 syntax by pull the request from github.

If my answer is wrong then edit it guys

solved Upgrade Xcode 7.3.1 Project to Xcode 8.0