The digital age may be practically synonymous with the Internet but that does not mean we are always connected. Though living without the Internet is like a horror story for many people, there are definitely periods within the day where users find themselves without a connection.
Some, for example, might have a daily commute that includes the underground. Others might visit locations where data connections are not possible, such as remote regions high up in the mountains. Regardless of the reason, developers now have to make sure that their apps can cope during periods of no connectivity, even if those apps usually rely on the Internet.

Online vs. offline

The reason why it is hard to create specific guidelines that apps should follow when they go offline is that connectivity is not of equal importance to all of them. A social app like Snapchat, for example, will require an Internet connection to share and receive pictures and videos and to update its daily filters. However, it does require a connection for the user to have fun with applying those filters and editing their photos.
As such, developers must determine the exact actions that require an Internet connection in their apps, and those that don’t. Then, the best course of action might be to allow for situations where losing connectivity breaks as little of the app’s functionality as possible.

Make data available locally

Most apps use very little data and phones nowadays usually come with considerable spare storage. This combination allows you to make the choice of having as much of the app’s data available locally as possible.
Of course, whether you can do that or not depends entirely on the type of app you are developing. Apps that require an Internet connection for security purposes, such as banking apps, simply cannot work in an offline mode.
The compromise for apps that usually require an Internet connection is to make at least some of the data available locally in a cached mode. That will allow users to continue interacting with the app, even if there is limited functionality or an actual time limit as they go through the cached content.

Syncing when a connection is ready

An additional way to ensure that the app can stay responsive even when users have a spotty connection is to allow it to sync data whenever there is a connection. In practice, this means that users can continue to interact with the app even when they are offline. Any changes they make will then be temporarily stored locally until their device can find a connection.
As one might expect, there are additional challenges in this process. For example, users might not wish to use up a lot of their mobile data so you will need to ensure that they have the option to only sync when they are connected to Wi-Fi.
If the app absolutely needs to sync some of the data the very moment a data connection is established, then it should at least use as little data as possible in mobile connections.

Don’t interrupt the user experience

For the final piece of the puzzle, developers must make the transition from online to offline as smooth as possible. Receiving an error message while using an app simply because the connectivity was lost can truly disrupt the user experience.
This is especially true now when the most-used apps in mobile have made significant advanced in offline features. Apps like Google Maps, for example, now offer a host of features offline, even though they might be limited in comparison to their online counterparts.