iCleaner can free up space in the following ways:
It deletes files sent and received via iMessage or MMS. The "smart" setting only deletes files that do not show up in any message, while "on" deletes all attachments (messages with attachments will show a blank space or icon).
It deletes cookies, browsing history and cache files to free up memory and preserve your privacy.
It deletes app caches, cookies, temporary files and snapshots. Furthermore, it detects popular applications to reclaim space that the built-in iOS cache management cannot.
More apps are added with each subsequent release. User data, useful cookies and other relevant files are left untouched.
It deletes downloaded iOS update files.
It deletes archived battery data, while leaving current battery data untouched.
It issues the apt-get autoremove command in order to remove packages installed as dependencies that are not needed anymore, and purges uninstalled packages.
This is disabled by default since it should only be used by experienced users who want to automate the operation. Note that removed packages and preferences are not included in the "analyze" filesize count.
It deletes log files and crash reports from known locations. These files are generally irrelevant to the user and can be safely deleted.
it scans and deletes system cache files and databases. Some of them are rebuilt upon respring, while other will be gone permanently. This helps free up space by removing obsolete cache data.
It deletes temporary files from your device. These files are meant to be removed automatically, but they often happen not to.
With this extremely powerful feature, you can add any file or folder to the cleanup process. Tap on "Add item" to add a new item to the cleanup, or an existing item to edit it.
Please use this with caution, as accidentally deleting critical files can force you to restore your device.
Read more about the custom cleanup configuration fields.