I am using the Xcode 8.0 GM. I created a default single-view app with my deployment target set to 9.0.
In my Podfile I\'m targeting the bleeding edge Swift 3 branch:
You should use the master branch now since the swift3 branch has been merged there. Moreover it's normal for the Xcode Migrator to show that many errors. What it's doing s compiling the code thinking it's a legacy Swift version but since it's already in Swift 3.0, the errors are to be expected. Finally, Xcode is asking you to convert to modern Swift syntax probably because you haven't used the latest version of Cocoapods to install Alamofire.
NB: event though Cocoapods tells you to use gem install cocoapods --pre, I prefer using gem update cocoapods --pre. Else, the older version of Cocoapods stays and still is used when using pod update. Check what version you're using with pod --version.