Apple has released the 6th developer preview build of OS X Yosemite to those registered with the Mac Developer Program. The update arrives as build 14A3429f, This preview 6 includes feature refinements and bug fixes, and is recommended for all Yosemite Dev Preview users to install.
If you are interested you can downloaded OS X Yosemite preview 6 from the Apple App store for the users who are using the prior versions of the Developer Preview builds of OS X 10.10. Even you can get the redeemable download code can be found on the Mac developer center for users yet to install it on their Macs.
Developer preview releases of OS X 10.10 are separate from the Yosemite Public Beta releases, Where latter remains at the first built up beta release. Developer Preview builds are intended for software developers, whereas the Public Beta is intended for additional bug detailing as well as receiving feedback about OS X Yosemite from end users.
Xcode 6 beta 6 separately includes the Yosemite and iOS software Development kit also available from the Mac developer center. The release data of this yet to announce by the Apple. Probably we can expect to release this in the month of October. Stay tune for more details and information regarding this OS X Yosemite.