Imagine that as a customer, you've signed into the little lemon mobile application to book a group reservation at a restaurant. You want to indulge yourself and some friends by enjoying a delicious pizza to celebrate your birthday next weekend. You provide the necessary information for your reservation by completing a series of steps via the mobile application. This includes the number of tables, a customized menu, and drink preferences. You also specify a music team to enhance your birthday experience. With only one step left to finalize your reservation, a friend calls to check on you. In haste to answer the call. You close the little lemon application. The call lasts a few minutes and you get back to completing your reservation. You open the app and to your surprise, the login screen displays the information you've provided is gone. At this point, you consider going to a different restaurant instead, nobody would blame you. That's not a great user experience. What is wrong with the application? The data you entered for your reservation is lost because the developers only store data in memory. Storing data in the application memory is a fast solution. It is also the least persistent. You can lose data stored in memory if the device is powered down, restarted, or in this case, the application was closed. Therefore, data that is critical to the app functionality or user experience should be persisted. Users can launch the app with all their information remaining in place. There are many ways to persist and store data in a React Native application. In this video, you'll explore the AsyncStorage library, one of the simplest storage options available. AsyncStorage is an asynchronous unencrypted key-value storage system for your React Native application. Key-value storage as a model for storing, retrieving, and managing dictionaries or hash tables. AsyncStorage also supports Android and iOS, offering different native implementations depending on the platform. On Android, AsyncStorage uses SQLite for the backend storage. SQLite is a database management system which you'll learn more about later. On iOS, there's native code that backs up AsyncStorage by storing small values in a serialized dictionary and larger values in separate files. How do you use AsyncStorage? The AsyncStorage library offers a JavaScript API to simplify your storage flow. This allows you to easily save, read, merge, and delete data. There are three methods that you will use which are; setItem, getItem, and removeItem. Let's begin with the setItem method. The setItem method stores a string value under a given key. You need to make sure to use different keys for different values. Otherwise, you may override existing data unexpectedly. The next method is getItem, which retrieves an existing value from storage based on a given key. Lastly, removeItem enables the deletion of an existing key-value pair in storage. Similar to the getItem method, you just have to pass the key. Let's highlight some of the benefits of using AsyncStorage. The first benefit is its simplicity. You can get up to speed and store values in a matter of minutes. By providing an intuitive API, we clearly defined methods. The second benefit of AsyncStorage is that it is asynchronous. This means that you can write and read data without blocking the main JavaScript thread. Finally, AsyncStorage is globally accessible. You can access your data from anywhere in the app. The only requirement is to import the module and use the corresponding methods. AsyncStorage is quite appealing, but there are some drawbacks. Let's explore these now. First, AsyncStorage is indeed known for its simplicity, but it's still an unencrypted key-value store. This means that it's not suitable for storing sensitive information, like authentication tokens or credit card numbers. Secondly, AsyncStorage is unable to provide protection against data loss. If the application is uninstalled or the device has reset, all data that lives in AsyncStorage will be lost. Finally, AsyncStorage is not the most performance solution for React Native applications. If performance is a concern other storage options may be more suitable. You'll discover these alternative storage options a bit later as you progress through this course. In this video, you learned about the importance of persisting data in a mobile application. You also learned that AsyncStorage is a possible solution you can integrate into your React Native applications with benefits such as its simplicity, asynchronous nature, and global access. But keep in mind it's not suited for sensitive data and doesn't protect you against data loss.
