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content/Frontend/React Native/OAuth2 login.md

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+Use #oauth2 login with React-Native
+
+## Common OAuth2 providers
+
+Can be handled by [react-native-app-auth](react-native-app-auth) by redirecting to url `com.yourapp://oauth2provider`. 
+
+### Example for #Google
+
+```typescript
+import { authorize } from 'react-native-app-auth';
+
+const GOOGLE_OAUTH_CLIENT = '...';
+
+// ...
+const authState = await authorize({
+  issuer: 'https://accounts.google.com',
+  clientId: `${GOOGLE_OAUTH_CLIENT}.apps.googleusercontent.com`,
+  redirectUrl: `com.yourapp:/oauth2redirect/google`,
+  scopes: ['openid', 'profile'],
+  dangerouslyAllowInsecureHttpRequests: true,
+});
+```
+
+### Example for #Yandex
+
+```typescript
+const YANDEX_OAUTH_CLIENT = '...';
+const YANDEX_OAUTH_SECRET = '...'; // better hide it somehow
+const APP_ID = 'com.yourapp';
+
+const authState = await authorize({
+  serviceConfiguration: {
+    authorizationEndpoint: `https://oauth.yandex.ru/authorize?response_type=code&client_id=${YANDEX_OAUTH_CLIENT}&redirect_uri=${APP_ID}:/oauth2redirect`,
+    // TODO: replace it with your own backend to secure client_secret:
+    tokenEndpoint: `https://oauth.yandex.ru/token?grant_type=authorization_code&client_id=${YANDEX_OAUTH_CLIENT}&client_secret=${YANDEX_OAUTH_SECRET}`,
+  },
+  clientId: YANDEX_OAUTH_CLIENT,
+  redirectUrl: `${APP_ID}:/oauth2redirect`,
+  scopes: ['login:info', 'login:avatar'],
+  dangerouslyAllowInsecureHttpRequests: true,
+});
+
+callback(authState.accessToken);
+```
+
+## Apple ID login
+
+[react-native-apple-authentication](https://github.com/invertase/react-native-apple-authentication) has its own [documentation](https://github.com/invertase/react-native-apple-authentication/tree/main/docs) on setting up OAuth using Apple ID.

content/Frontend/React Native/Preserve FlatList scroll position in React Native.md

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+Sometimes you need to keep scroll position of `FlatList` in React Native after some user interactions.
+
+```typescript
+// interact() is doing some stuff, that changes FlatList scroll size
+type Props = { interact: () => void; }
+
+const SomeList: FC<Props> = ({ interact }) => {
+  const scrollPosition = useRef(0);
+  const scrollHeight = useRef(0);
+  
+  // set it to `true` before interaction and back to `false` right after
+  const shouldKeepScrollPosition = useRef(false);
+
+  const onScroll = useCallback(
+    (event: NativeSyntheticEvent<NativeScrollEvent>) => {
+      scrollPosition.current = event.nativeEvent.contentOffset.y;
+    },
+    [],
+  );
+
+  const onContentSizeChange = useCallback((_: number, h: number) => {
+    if (!shouldKeepScrollPosition.current) {
+      scrollHeight.current = h;
+      return;
+    }
+
+    ref.current?.scrollToOffset({
+      offset: scrollPosition.current + (h - scrollHeight.current),
+      animated: false,
+    });
+
+    scrollHeight.current = h;
+  }, []);
+
+  // onInteraction wraps interaction to preserve scroll position
+  const onInteraction = useCallback(
+    () => {
+      shouldKeepScrollPosition.current = true;
+
+      setTimeout(() => {
+        interact();
+      }, 0);
+
+      setTimeout(() => {
+        shouldKeepScrollPosition.current = false;
+      }, 500);
+    },
+    [setSelectedSubThemes],
+  );
+  
+  return (
+    <FlatList
+      // ...required FlatList options
+      ref={ref}
+      onContentSizeChange={onContentSizeChange}
+      onRefresh={onRefresh}
+      onScroll={onScroll}
+    />
+  )
+}

content/Frontend/React Native/Useful comands.md

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+## Show android logcat
+
+```shell
+adb logcat com.application:I "*:S"
+```
+
+## Get .apk's SHA-256 
+
+```bash
+keytool -printcert -jarfile "$1"
+```
+
+## Assemble debug release on Android
+
+Packages release with bundled resources. 
+
+```shell
+npx react-native bundle \
+  --platform android \
+  --dev false \
+  --entry-file index.js \
+  --bundle-output android/app/src/main/assets/index.android.bundle \
+  --assets-dest android/app/src/main/res/
+
+cd android && ./gradlew assembleDebug
+
+# do your stuff
+
+./gradlew clean
+```
+
+## Send release to Android device
+
+```shell
+cd ./android \
+  && ./gradlew assembleRelease \
+  && adb install ./app/build/outputs/apk/release/app-release.apk
+```
+
+## Deep links
+
+- https://zarah.dev/2022/02/08/android12-deeplinks.html
+- https://developer.android.com/training/app-links/verify-site-associations#invoke-domain-verification
+- https://digitalassetlinks.googleapis.com/v1/statements:list?source.web.site=https://miin.ru&relation=delegate_permission/common.handle_all_urls
+
+### Open deep links
+
+```shell
+# ios 
+xcrun simctl openurl booted $1
+
+# android
+adb shell am start -W -a android.intent.action.VIEW -d $1 \
+com.application
+```
+
+### Reverify links on Android
+
+```shell
+PACKAGE="com.application"
+
+adb shell pm set-app-links --package $PACKAGE 0 all && \
+  adb shell pm verify-app-links --re-verify $PACKAGE
+```
+