U2 frontman Bono has expressed his pride at the partnership his band forged with Apple in releasing their latest album "Songs of Innocence" for free on iTunes, reports Billboard.

Speaking at the Web Summit conference in Dublin, Bono addressed questions about the controversial "giveaway" of their album. "It's one of the proudest things for us ever," the rocker said.

"We were just thrilled that we got a chance to introduce ourselves to people who weren't fans to listening to rock music, or people that listen to Bhangra in India, or whatever, all around the world," he continued.

"100 million people checked us out and listened to two or three tracks. And 30 million people actually listened to the whole album. So we did in three weeks with Songs of Innocence what took us 30 years with 'The Joshua Tree,'" he added.

The promotion received backlash from many of the 500 million subscribers of iTunes, according to UK's The Independent.

Many of those who were not fans of the band took to social media to air their grievances. Musicians and critics alike were not very pleased with the PR ploy.

"I did not [know] you were on my phone. It's legit like waking up with a pimple or like a [herpes]. IDK. I [didn't] know you were on my phone. What the f***k," tweeted rapper Tyler, The Creator upon learning that he has U2's new album on his library without downloading it.

A month after the surprise release, Bono issued an apology for the automatic iTunes download, says The Guardian.

In a question-and-answer session hosted on Facebook, Bono apologized as an answer to a user who pleaded for U2 not to release an album that will automatically download on Apple devices.

"Oops, I'm sorry about that," said Bono. "I had this beautiful idea and we kind of got carried away with ourselves."

Due to popular demand, Apple has released a step-by-step instruction on their website on how to remove the "iTunes gift album" from the music libraries of Apple device owners.

U2 and Apple appear to not be done with collaborating yet as Bono has hinted at another partnership, says Venture Beat. "They let us into the labs," the bespectacled rocker teased.