WASHINGTON — President Trump marked his first 100 days in office by attacking the news media with a calculated fury not seen since the beginning of his administration — while rewarding the journalists he allegedly loathes with long, newsy chats in the Oval Office, Air Force One rides and meals.

Mr. Trump’s split-personality approach to the press was on particular display on Saturday, when he skipped the White House Correspondents’ Association Dinner to blast the news media in front of a friendly rally audience in Harrisburg, Pa., and then sat down with John Dickerson, host of CBS’s “Face the Nation,” for a wide-ranging conversation.

The interview was the capstone of a frenetic period in which Mr. Trump sat for interviews with representatives of the very media he has publicly criticized and dispatched his top advisers to provide virtually nonstop briefings for them. The president and his aides made the case that he had accomplished significant things since taking office, despite Mr. Trump’s lack of major legislative achievements.

In his interview with Mr. Dickerson, the president veered from sales mode to sullen defiance. The first part, which aired on Sunday, was all sales. The second part, which aired on Monday, ended when Mr. Trump walked away abruptly after Mr. Dickerson pressed him on his false claim, expressed on Twitter, that President Barack Obama had placed a “tap” on Trump Tower.