Apple chief executive Tim Cook has made a surprise visit to China.

Though in an upbeat mood as he met gamers in the city of Chengdu, the company faces flagging iPhone demand in the country, analysts suggest.

It is his second trip to China this year – in March he said Apple had a “symbiotic” relationship with China, a key manufacturing base.

But the firm’s operations in the country have been complicated by Covid and US-China tensions.

Mr Cook’s visit included a trip to Apple’s Taikoo Li store to meet young players of Tencent’s Honour of Kings online battle game.

“The energy tonight was off the charts!” he wrote on the Chinese social media platform Weibo.

Honour of Kings started in Chengdu but was now “a global phenomenon on the App Store”, he told the state-run China Daily newspaper.

He hoped that Chinese developers could repeat this success with software for Apple’s new Vision Pro augmented reality headset, which would also use a Chinese manufacturer, the report said.

This year marks Apple’s third decade in the country.

Mr Cook, who has been CEO since 2011, is regarded as the architect of Apple’s embrace of Chinese manufacturing, but the relationship has had its ups and downs in recent years.

Covid restrictions hit production in China, and geopolitical tensions with the US have added to supply chain concerns. Recently the company has sought to increase production in India.

Sales of its latest iPhone have not matched previous models, according to analysts who spoke to Bloomberg. They blamed sinking demand in China, and intensifying competition from rivals.

Tough US export controls on advanced technology have made it hard for Chinese firms such as Huawei to produce models that can match the iPhone.

But the launch in August of Huawei’s sell-out Mate 60 Pro phone, which contained advanced Chinese-made chips, suggested rivals were catching up.

Mr Cook’s visit coincides with news of other Chinese tech advances.

Chinese tech giant Baidu revealed on Tuesday that it had released the latest version of its Ernie AI model.

Ernie 4.0 was, it claimed, a match for OpenAI’s GPT-4 system

At a launch event led by Baidu chief executive Robin Li, the AI was shown writing a martial arts novel and creating advertising posters and videos.

China now has a number of domestically developed large language models, but AI developers face tight restrictions.

And when the BBC tried out an earlier version of Ernie the bot deflected questions about sensitive subjects such as the date of the Tiananmen Square crackdown (4 June 1989), or the name of a jailed former senior Communist Party figure (Bo Xilai), with the response: “Let’s talk about something else.”