Apple has reportedly inked a contract with Sony Music for the soon-to-be-released iRadio service, a source with knowledge of the negotiations told AllThingsD. Apple already has deals with Warner Music and Universal Music, according to earlier reports.

The deal with Sony marks the completion of Apple's efforts to sign the three biggest major music labels in the recording industry ahead of the official iRadio launch. Apple has been racing to prepare the music streaming service in the past few weeks, but according to earlier reports the company is still working to secure a deal with Sony/ATV, a separate branch of Sony that publishes music.

Apple has been working towards the official iRadio launch since last fall, but it has been bogged down in multiple contract negotiations with music industry executives still wary of embracing digital stream. The new service isn't expected to officially launch at WWDC, although Apple may use the opportunity to tell developers how it will work.