So, this is where swift lives, after you've installed XCode 6 Beta:

/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift

Also, there's a directory named swift which has various libraries:

/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift

To start playing in a terminal:

export PATH=/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin:$PATH

You could also change this in XCode 6's Preferences.

I use it via xcrun:

$ xcrun swift -v -o test test.swiftSwift version 1.0 (swift-600.0.34.4.5)Target: x86_64-apple-darwin14.0.0/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c -primary-file test.swift -enable-objc-attr-requires-objc-module -target x86_64-apple-darwin14.0.0 -module-name test -sdk /Applications/Xcode6-Beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -color-diagnostics -o /var/folders/2p/rs8p19s957ggyxzntnj3tp_40000gn/T/test-bb5ff8.o/usr/bin/ld /var/folders/2p/rs8p19s957ggyxzntnj3tp_40000gn/T/test-bb5ff8.o -force_load /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/arc/libarclite_macosx.a -syslibroot /Applications/Xcode6-Beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -lSystem -arch x86_64 -L /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/macosx -rpath /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/macosx -macosx_version_min 10.10.0 -no_objc_category_merging -o test

Note however the swift libraries are loaded (via @rpath) from /Applications/Xcode6-Beta/.../swift/macosx so the binary won't work on another system unless it's got the same version of Xcode installed in the same place. Unless you want to do lots of copying/install_name_tool calls to sort it out...

$ otool -l test |fgrep path         name @rpath/libswiftAppKit.dylib (offset 24)         name @rpath/libswiftCoreGraphics.dylib (offset 24)         name @rpath/libswiftDarwin.dylib (offset 24)         name @rpath/libswiftDispatch.dylib (offset 24)         name @rpath/libswiftFoundation.dylib (offset 24)         name @rpath/libswiftObjectiveC.dylib (offset 24)         name @rpath/libswift_stdlib_core.dylib (offset 24)         path /Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.x

1. 安装xcode 6 beta

2. 设置路径：

export PATH=/Applications/Xcode6-Beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin:$PATH

3. vim test.swift

println("Hello swift")

4.

xcrun swift -v -o test test.swift

5 ./test