http://www.usatoday.com/story/tech/news/2016/04/06/weird-trick-free-up-space-your-iphone/82698454/
This iPhone trick appeared on Reddit last month (hat tip to Cnet), and it requires users to rent a movie. Sort of.
Here’s how it works:
Go to Settings: Once there, tap General > About. Scroll down until you find “Available,” which tells you how much storage space you have.
Head to the iTunes Store: Pick the HD movie of your choice available for rental. Don’t worry, you're not paying to rent a movie, but pick a big download. For example, the HD version of The Avengers is 6.5 GB. Hit Rent two times. You’ll see a spinning wheel, then receive the “there is not enough available storage” message.
Repeat as often as needed: When you tap Settings and return to the About section, you should have more storage space. It may be small, but do this enough times and you can add as much as a couple gigabytes.
Eventually, you will reach a point where you can no longer gain storage space.
I tried this on an iPhone 5S with 900 MB of available storage, performing this trick a few times. I finished with 3.8 GB of storage.
What appears to be happening is the iPhone is clearing out the caches and other data from apps on the device to make more room. I noticed right after trying to “rent” the movie, the iTunes Store icon read “Cleaning” for a short period. Digging deeper into Settings > General > Storage & iCloud Usage > Manage Storage, I also noticed some of my apps were taking up less storage space.
One more important note: be sure to check your storage space after each attempt so you don't end up with enough space for the movie rental to clear.
