Let iOS apps with external event handling report onApplicationWillResignActive.
Defined in <SDL3/SDL_system.h>
void SDL_OnApplicationWillEnterBackground(void);
This functions allows iOS apps that have their own event handling to hook into SDL to generate SDL events. This maps directly to an iOS-specific event, but since it doesn't do anything iOS-specific internally, it is available on all platforms, in case it might be useful for some specific paradigm. Most apps do not need to use this directly; SDL's internal event code will handle all this for windows created by SDL_CreateWindow!
It is safe to call this function from any thread.
This function is available since SDL 3.1.3.