"Spectre," the 24^th James Bond film, released its official theme song, and is now available on iTunes. Sam Smith sang and wrote, together with Jimmy Napes, the "Writing's on the Wall."

Earlier, Smith, who expressed his gratitude for the support of his fans over Twitter, received compliments for doing a great job with his new song.

"Thank you for all your amazing messages. Today is such a special day for me and I am so grateful to everyone supporting this track xx," the British singer tweeted.

Welshpaula responded to Smith's post, and told him to enjoy every second of today, because it's his day. She said the track was amazing, and told the singer that they loved him.

"Oh my dear Sam no one else could do this as beautiful as U did! #SPECTRE #WritingsOnTheWall #bond #SamSmith," SamSmith isthe Best ‏added on the comment.

Jo Rowling expressed admiration for Smith's voice through her comment, while Val Bayliss-Brideaux said that the song set the tone for "Spectre."

Rumors started spreading, earlier this summer, about the singers who would potentially sing the official movie track for "Spectre," but Smith told his fans that he didn't know about the recording plans, the Rolling Stone reported.

What fuelled the massive speculation that he will be singing "Spectre's" new theme was when he tweeted a black-and-white snap, wearing a ring similar to the one which appeared in the film's trailer. He confirmed his involvement with the project, a few hours later, via a tweet.

Meanwhile, a source reportedly said that Smith wasn't the first choice to sing the new James Bond theme, NDTV learned via Daily Mirror's report.

The source reportedly said that Adele was Bond's, played by Daniel Craig, first choice. Craig was keen, and director Sam Mendez was having second thoughts, whether to use her voice or a new one.

"Filmmakers were prepared to offer millions, but Adele was never up for it. How do you top a worldwide hit like Skyfall anyway? It was too big a risk," the source added.

The producers, according to the report, decided to give the project to Smith. There are no official statements yet, from Smith, pertaining to this news.