iCleaner can free up space by removing unnecessary files from your device. The cleanup process is made of the following steps:
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 icon).
it deletes cookies, browsing history and cache files to free up memory and preserve your privacy.
it deletes App Store app caches, cookies, temporary files and snapshots. Furthermore, it detects popular applications for a more in-depth cleanup.
OTA software updates:
it deletes downloaded iOS update files.
it cleans up Cydia caches and temporary files, cache files generated by Cydia apps and tweaks, partially downloaded packages and repo files.
it purges local package lists for your Cydia sources. Only useful if they aren't updating correctly due to corrupt lists.
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. This helps 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.
iCleaner features a custom cleanup pass based on file extensions. By default, it looks for log and temp files all over the directory tree.
Custom files and Folders cleanup:
with this extremely powerful feature, you can add any file or folder to the cleanup process. Check the user guide
for a detailed explaination of how it works.