Closing Recent Apps on iPhone Causes Battery Drain?

Android users often do it to free up RAM, and it does happen quite frequently, especially on forked Android systems like ColorOS, EMUI, or MIUI. Phones tend to feel sluggish when too many apps are open and running in the background.

However, iOS users don't need to worry about it. In fact, it is advisable not to close open apps in the background.

The iOS operating system works differently from Android. When an app is not in use and is moved to the background by iOS, its status is frozen. This is unlike Android, where an app remains open when it is in the background. This 'freeze' condition is similar to a sleep state. The app becomes inactive and leaves only a small amount of information in RAM as a 'marker' to return the app to its state before being deactivated. One clever trick Apple uses in designing iOS is that when an app is moved to the background, it saves a kind of 'screenshot' of the app's last state, so when we open it, it appears as if we are getting the last state before moving the app to the background. However, at that moment (in just a fraction of a second), iOS 'mobilizes' all its resources to reopen the app and restore it to its last state before deactivation. This is an efficient and power-saving scenario—one of the main advantages of iOS.

You might wonder, then, why notifications on iOS devices are very real-time and keep running even though the app is in a 'freeze' state. The answer is that notifications go directly to Apple's server and are sent in real-time to the device. So, in reality, notifications run separately from apps. If you want to see the proof directly, it's easiest when you receive an email notification. Try opening the email app (not from the notification but by tapping the icon of the email client used). You will notice the app synchronizing when opened, and the email that was visible in the notification just arrived when you open the email app. There is a visible delay, even if only for a fraction of a second when opening the email app.

Now, due to this fact, if you close apps in the background on iOS, the device will require more resources, including processor performance, RAM, and, of course, battery. Closing and reopening apps on iOS is actually more power-consuming and may even make opening apps slower. Therefore, when using iOS, it is advised not to bother closing apps visible in the background.