I don't think that menu does what you hope...
The choices being:
- current swift syntax
- modern Obj-C syntax
- Obj-C w/arc
There is no 'Obj-C to Swift' choice.
Quoting from Apple's Swift blog 10.2016:
OS X El Capitan requires Xcode 7, which includes Swift 2, native support for System Integrity Protection (SIP), app thinning, as well as the latest SDKs. When running Xcode 7 you may notice a number of syntactical changes need to be applied to your Swift 1.2 code. To help in your migration to Swift 2, Xcode 7 includes a helpful tool to re-write older Swift code for you. Just select the menu item Edit > Convert > To Latest Swift Syntax and Xcode will migrate your code to the latest Swift API and syntax.