Generic functions for loading and saving values with AsyncStorage in React Native.

AsyncStorageGenericUtils.ts

import {AsyncStorage} from 'react-native';

export function setValue(key: string, value: any): Promise<void> {
  return AsyncStorage.setItem(key, JSON.stringify(value));
}

export function getValue<T>(key: string, defaultValue: T = null): Promise<T> {
  return new Promise((resolve, reject) => {
    AsyncStorage.getItem(key).then((value) => {
      if (value !== null) {
        resolve(JSON.parse(value));
      } else {
        resolve(defaultValue);
      }
    }).catch( (error) => {
      reject(error);
    });
  });
}