iOS almost working

src/screens/Compose/Root/Header.tsx

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+import {
+  getLocalActiveIndex,
+  getLocalInstances
+} from '@utils/slices/instancesSlice'
+import { StyleConstants } from '@utils/styles/constants'
+import React, { useContext } from 'react'
+import { StyleSheet, View } from 'react-native'
+import { useSelector } from 'react-redux'
+import ComposeContext from '../utils/createContext'
+import ComposePostingAs from './Header/PostingAs'
+import ComposeSpoilerInput from './Header/SpoilerInput'
+import ComposeTextInput from './Header/TextInput'
+
+const ComposeRootHeader: React.FC = () => {
+  const { composeState } = useContext(ComposeContext)
+  const localActiveIndex = useSelector(getLocalActiveIndex)
+  const localInstances = useSelector(getLocalInstances)
+
+  return (
+    <>
+      {localActiveIndex !== null &&
+        localInstances.length &&
+        localInstances.length > 1 && (
+          <View style={styles.postingAs}>
+            <ComposePostingAs />
+          </View>
+        )}
+      {composeState.spoiler.active ? <ComposeSpoilerInput /> : null}
+      <ComposeTextInput />
+    </>
+  )
+}
+
+const styles = StyleSheet.create({
+  postingAs: {
+    marginHorizontal: StyleConstants.Spacing.Global.PagePadding,
+    marginTop: StyleConstants.Spacing.S
+  }
+})
+
+export default ComposeRootHeader