How to Make Your App Available Offline

These days, users want applications to perform even when they are not online. Otherwise, a poor network connection translates into a poor user experience. Push notifications, in-app messaging, and offline mode help to retain users. Offline mode is a must for delivery apps with GPS navigation, apps for urgent medical assistance, and banking apps.

What Are Offline Mobile Apps?

WhatsApp is the trendiest messaging app that people are using round-the-clock these days. The app works with an internet connection and you cannot send a message without the internet connection.

Thereby, offline apps are the applications that work even when your internet connection gets disconnected and you can resume the application, from where your connection is terminated.

Users appreciate apps with offline mode because:

- These apps constantly work without delays.

- They want to keep working without an internet connection.

- Apps with offline mode load quickly.

- Offline apps hardly drain a phone’s battery.

Even if an app is appreciated by users, a lack of offline functionality can make them seek alternatives. The notion, a note-taking app, is criticized for working without offline mode.

How to decide on offline features for your app

Unfortunately, there’s no one-size-fits-all approach or magic wand to create the ideal offline mode for your app. You have to do your own homework, but here’s a formula that may help:

1. Analyze your workflow, determine your business needs, and translate them into app features.

2. Decide what you want to achieve through your app.

3. Prioritize these features as ones your business can't live without, ones that are important but not absolutely urgent, and ones that would be nice to have.

Sharing this information with your developers will help them understand your business goals and suggest the proper technologies for a well-tailored solution.

To decide on offline functions, you can use the well-known Eisenhower Decision Matrix. It will help you see what’s important and what isn’t. To fill out the matrix:

1. Write down features and interactions that you want to be available offline.

2. Interview users to determine how important each feature/interaction is for them.

3. Define how difficult it will be to implement each feature.

4. Put this information into the matrix and prioritize.

As a result, you’ll have a list of offline features and will be ready to figure out how to implement them.

Ensuring data sync for web and mobile apps

When an app is used offline, there are many actions and much data you have to sync with the server. This syncing can happen whenever an internet connection is available. For web apps, user actions can be stored in IndexedDB as jobs to sync. As soon as the network is available, these jobs can be processed one by one. With a mobile app, it’s likely you’ll have both client- and server-side storage. Let’s look at the details of data syncing for web and mobile apps.

Offline sync for a web app

When you store offline data in the browser, you have to upload it to the server whenever the network is available. To make sure data syncs properly, do the following:

- Determine the smallest amount of data to store locally.

- Select as little data as possible to transfer from the server to the device.

- Set a trigger to initiate the sync, manually or in the background.

- Configure conflict resolution.

- Identify and prioritize data sets for syncing.

- Indicate the factors that will trigger a sync.

- Establish a balance between sync frequency and battery drain.

- Elaborate the retry mechanism.

- Send a sync status notification to users.

Offline sync for a mobile app

Using an offline app, users can take actions offline and then synchronize changes with a central repository. To do this, your app will need to manage the flow of information between the server and client.

In most cases, offline mode is used in situations when users can edit information on the server-side and on the mobile side. This is the best-case scenario. Even though it may be alluring to create offline apps supporting two-way sync, it’s the most complicated method.

If you support two-way sync, your synchronization logic has to ensure that data is up to date on the mobile and server sides simultaneously. There are a number of data storage methods to make an app work offline, and they differ for iOS and Android.

Android. The Android platform offers SharedPreferences APIs that can be used for saving a comparatively small amount of primitive data in key-value pairs. Put simply, a SharedPreferences object is a reference to a file with key-value pairs. When using SharedPreferences, you have a key (which is a string) and the value for that key.

The value can be a boolean, float, int, long, or string. Android stores all SharedPreferences files as XML files in a private directory. An app may contain various SharedPreferences files. There are methods which can be used for receiving a SharedPreferences object. One of them is used if an app contains a single preference file.

The other is used if an app contains more than one preferences file or if you want to give a custom name for the SharedPreferences instance.

iOS. To implement offline mode for an iOS app, you can use the NSUserDefaults class to save and update users’ preferences. The NSUserDefaults class delivers a programmable interface, allowing an app to customize its behavior according to a user’s preferences.

For instance, you can enable users to save a profile picture offline or add a function that automatically saves documents. The app records such preferences in the user defaults system. In such a way, data is cached, helping you avoid opening the user defaults database whenever you need a default value.

As this default system is available within your app’s code, any data saved to it will persist across app sessions. When a user closes your app or resets their mobile devices, they still can use the saved information the next time they enter the app.

Offline Access Benefits Your App

It’s understandable that certain apps cannot be made fully offline. However, most of them can choose to make at least a portion of their data accessible with no internet connection.

Allowing an app to work offline ensures better UX, a leg up on the competition, and greater customer loyalty.

Frequently Asked Questions

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