BackHandler Fix.

Hi! 👋

Firstly, thanks for your work on this project! 🙂

Today I used [patch-package](https://github.com/ds300/patch-package) to patch `native-base@3.4.28` for the project I'm working on.

Here is the diff that solved my problem:

```diff
diff --git a/node_modules/native-base/src/hooks/useKeyboardDismissable.ts b/node_modules/native-base/src/hooks/useKeyboardDismissable.ts
index f3cfa44..8074119 100644
--- a/node_modules/native-base/src/hooks/useKeyboardDismissable.ts
+++ b/node_modules/native-base/src/hooks/useKeyboardDismissable.ts
@@ -42,18 +42,18 @@ export const useKeyboardDismissable = ({ enabled, callback }: IParams) => {
useBackHandler({ enabled, callback });
};

+
export function useBackHandler({ enabled, callback }: IParams) {
useEffect(() => {
- let backHandler = () => {
+ if (!enabled) return;
+
+ const backHandler = () => {
callback();
return true;
};
- if (enabled) {
- BackHandler.addEventListener('hardwareBackPress', backHandler);
- } else {
- BackHandler.removeEventListener('hardwareBackPress', backHandler);
- }
- return () =>
- BackHandler.removeEventListener('hardwareBackPress', backHandler);
+
+ const subscription = BackHandler.addEventListener('hardwareBackPress', backHandler);
+
+ return () => subscription.remove();
}, [enabled, callback]);
}
```

This issue body was [partially generated by patch-package](https://github.com/ds300/patch-package/issues/296).

Start in src/hooks/useKeyboardDismissable.ts and inspect useBackHandler and its hardwareBackPress listener lifecycle. Compare the reported behavior with the supplied diff and verify that the listener is registered and cleaned up correctly; done means the BackHandler problem is fixed without regressions.

Written by the indexing model from the issue text.