Скачать или смотреть How to Properly Store Variables in Memory with Swift

Discover how to effectively store and retrieve variable values in a Swift app, ensuring data persistence even after the app is closed.
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How to Properly Store Variables in Memory with Swift

When developing an iOS app, you might find yourself needing to keep track of certain values even after the user closes the app. This requirement is particularly common in scenarios where your app collects and processes data from an API based on the device's battery state. In this guide, we'll explore how to handle this situation by storing variables to memory using Swift.

The Problem

Imagine you have an app that collects battery data whenever the device is charging. You want to store the battery values so that they persist across app launches, allowing users to see data from their previous sessions. However, when you close and reopen the app, all data is lost, and you're left wondering if this is expected behavior or if you’ve made a mistake in your variable declaration.

To summarize the details you've provided:

You are observing that your variables reset upon closing the app.

You have two potential reasons behind this behavior:

It might not be possible to retain data in the way you're attempting.

You might not be declaring your variables correctly.

The Solution

To solve this issue, you can utilize UserDefaults, which is a built-in way in iOS to store small amounts of data persistently. This allows you to save user preferences or other small data types, like floats or integers. Let’s walk through the steps to get this working.

Step 1: Declare Your Variables

Instead of setting your variables as simple floats that reset every time your app is closed, you can utilize UserDefaults to store them. Here’s how you can declare your variables:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update Your Data Collection Function

Within your function that responds to battery state changes, you should set the variables to track the charging values, and then save them in UserDefaults:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Retrieve Stored Data When Needed

Whenever your app launches, or you need to access the most recent battery data, pull the last stored value from UserDefaults like so:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following these steps, you can effectively retain data in your Swift application between sessions. This approach not only prevents data loss when the application is closed but also enhances the user experience by providing persistent and accessible data.

Implementing UserDefaults is a straightforward solution for minor data storage needs, so be sure to leverage it in your apps. If you run into other challenges implementing this, don’t hesitate to reach out for further assistance.

Feel free to try this in your app and bring your project to the next level with reliable data handling!