# SDL_OnApplicationWillEnterBackground

Let iOS apps with external event handling report onApplicationWillResignActive.

## Header File

Defined in [<SDL3/SDL_system.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_system.h)

## Syntax

```c
void SDL_OnApplicationWillEnterBackground(void);
```

## Remarks

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](SDL_CreateWindow)!

## Thread Safety

It is safe to call this function from any thread.

## Version

This function is available since SDL 3.2.0.

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[CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategorySystem](CategorySystem)