Clearing your cache is a great way to speed up your iPhone (or iPad). Here's how to remove unwanted files and make your device perform at its best.
Deleting the cache in Safari is simple.
Data stored by other apps can be cleaned out using the Usage option in Settings.
Tap Settings -> General -> iPhone Storage.
At the bottom of the screen (space-saving recommendations below), you'll see your apps sorted by space used. Click on an application that takes up a lot of space.
If you decide to proceed, tap Delete App, confirm, then head to the App Store (or your Purchased list) and re-download it. This clean install won't include the data and documents and will, therefore, be smaller.
There are many applications that quickly and efficiently remove junk files. They are usually downloaded to a Mac or PC; then connect your iPhone (or iPad) and run the application.