In this serial of articles, we will explain "How to gain more storage space on iPhone/iPad".
If you like me, wake up the next morning and find out that the iPhone is simply out of memory, it's probably because of the update patch of iOS.
Remove pending iOS updates
iOS automatically downloads a new software update over Wi-Fi and prompts you to install it. Should you decide to skip installing a downloaded software update, you can regain anywhere from a few hundred megabytes to a few gigabytes of storage simply by deleting the pending iOS installer.
Go to Settings → General → iPhone Storage, Tap the software download in the list and select Delete Update.