LONDON — Apple’s next CEO John Ternus is a company veteran who rose through the iPhone maker’s hardware engineering ranks but until now has maintained a low profile. Ternus will take over as chief executive in September for Tim Cook, who turned Apple into a US$4 trillion tech colossus during his 15-year run after the death of co-founder Steve Jobs. Ternus faces challenges that will force him to step out of his comfort zone in hardware engineering. Beyond finding ways to keep Apple competitive in the artificial intelligence race, he will need to navigate supply chain questions and relationships with...