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.
OTA software updates:
it deletes downloaded iOS update files.
Battery usage data:
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.
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.