storage.jsx

async loadFromStorage() {
  try {
    const value = await AsyncStorage.getItem(STORAGE_KEY);
    if (value !== null) {
      this.setState({
        api_key: value
      });
    }
  } catch (error) {
    console.log(`AsyncStorage error: ${error.mesage}`);
  }
}

async writeToStorage() {
  this.setState({
    api_key: this.state.input_value
  });
  this.fetchData();
  try {
    await AsyncStorage.setItem(STORAGE_KEY, this.state.input_value);
  } catch (error) {
    console.log(`AsyncStorage error: ${error.message}`);
  }
}