Former President Barack Obama told Prince Harry in an interview broadcast Wednesday that people in leadership roles must be careful in their use of social media and warned against spending too much time immersed in the internet at the expense of the world outside.

He did not, however, directly mention his successor, President Donald Trump, who has made the use of Twitter a centerpiece of his presidency.

"All of us in leadership have to find ways to recreate a common space on the internet," He said. "One of the dangers of the internet is people can have entirely different realities. They can be just cocooned in information that reinforces their current biases."

He spoke with Harry in the prince's capacity as guest editor of the BBC Radio 4 news program. Both men said the interview, recorded in Canada in September, was Obama's first since leaving the presidency in January.

Obama said he felt serene the day he left the White House at the end of his second four-year term despite the vast amount of work that remained unfinished. He said it was "hugely liberating" to be able to set his own agenda in the morning to have the time to talk with his wife, Michelle, now that he is no longer president.

"I miss the work itself because it was fascinating," Obama said of his eight years in the Oval Office, citing his health care reforms as one of his proudest achievements.

In a brief live segment at the end of the show, Harry said he did not know if Obama would be on the guest list for his wedding in May to American actress Meghan Markle.

"I don't know about that, we haven't even put the invite or the guest list together, who knows if he's going to be invited or not," Harry said. "I wouldn't want to ruin that surprise."

The Sun newspaper, a popular tabloid, has suggested that the British government is concerned that Harry and Markle may invite the Obamas but not Trump, possibly straining ties between the two governments.

Harry did say his fiancee enjoyed her first Christmas with the royal family.

"She really enjoyed it, and the family loved having her there," Harry said.

Harry used his position to ask Obama a "lightning round" of questions of the type normally asked of entertainers, not politicians.

The former president declined to say whether he wears boxers or briefs, preserving a bit of post-presidential dignity, but was willing to say he prefers Aretha Franklin to Tina Turner — "Aretha is the best," he said of the Queen of Soul — and favors retired basketball star Michael Jordan over current phenom LeBron James.

Obama rejected gloomy prognostications about the state of the world, saying that in many ways the world is healthier and wealthier than it has ever been, making it perhaps the best time in human history to be born.

He cited improved treatment of African-Americans and greatly expanded opportunities for young women as achievements of the past few generations that give him hope for the future.

Harry also interviewed his father, Prince Charles, who offered a more gloomy assessment. He said the root causes of climate change are not being addressed even as it caused "untold horrors" in different parts of the world.