Apple’s Chief Executive Steve Jobs will attend the company’s upcoming annual Worldwide Developer Conference (WWDC) 2011, the Cupertino, California-based gadget maker confirmed.

Mr. Jobs’ presence at the WWDC was in doubt as he has been on medical leave since January. It is Job’s second such leave since he was first diagnosed with pancreatic cancer in the year of 2004.

Mr. Jobs is expected to deliver the keynote speech at the conference that will take place next week in San Francisco.

The confirmation of Mr. Jobs’ presence at the WWDC appears to have cheered up investors, who are concerned about the health of powerful and influential chief. Shares in Apple gained more than 10 points in the after-hours trading on Tuesday.

Apple also announced that it would use its upcoming developer conference to introduce its iOS 5, Mac OS X and the much-rumored cloud music service iCloud.

Meanwhile, The Wall Street Journal reported that Apple has hit agreements with several music labels, including Warner Music Group, EMI and Sony Music Entertainment, for its iCloud music service.