I write native Apple software (Swift/UI/App/WatchKit), and my server stuff is PHP (and works great).

I like to spend as little time as possible on the backend. I totally admit its not my strong suit, so having a robust, highly-supported, standardized, performative, language like PHP, with a gazillion assistive resources and examples around, is nice. I've been writing stuff in PHP for over 20 years, so I sort of know my way around it.

I'll be expanding my Apple native stuff into the new "pseudo-reactive" realm of SwiftUI, but I don't really plan to keep growing my backend chops. PHP is doing fine for me. If I need anything else, I'll hire the talent.