The simple hack to free up space on your iPhone without deleting content

An easy trick, which has allowed some Apple iPhone users to free up hundreds of megabytes and occasionally a few gigabytes, has been revealed.

Users have been able to get extra space on their device by attempting to rent a film that requires more space than is available on their smart phone, The Sun reports.

The report claims that the phone can free up a surprising amount of storage by clearing saved caches in Apple apps.

Some users have reported freeing up to 9GB on their mobile using the hack. Results may vary and the trick seems to work best for older models of iPhones and those with just 16GB of factory space.

This is how it has worked for iPhone users:

1. Check how much space you already have

Open your phone's Settings, selected General and About.

This will give you a run down of the amount of data on your device.

You can see how much room you have left on your phone in the About section in Settings. Photo: Supplied

2. Open the iTunes Store

Head to the film section of the app and search for a long movie - maybe the 1963 feature Cleopatra, which runs for more than five hours or any of the Lord of the Rings films.

The movie needs to be larger than the amount of space available on your phone.

You then need to tap the Rent button twice, bearing in mind you won't actually be paying for the film as you won't have enough space for it on your device.

3. It's that simple

When you try to rent one of these large films, the iTunes store will show a notification saying that you do not have enought storage to download it.

The message that comes up when you try to rent a film you don't have enough room for. Photo: Supplied

This should mean that the iOS has freed up some space already.

Go back to the about page and you should see a few hundred megabytes of extra space in your available section.

It's not clear exactly why or how it works, it is likely the Apple operating system is clearing out caches of retained data in various apps.

Apple's pre-installed apps often save data automatically, such as free song previews from the iTunes store - it is this data that is likely being removed by iOS to create the additional free storage space.

4. Repeat as required

You can repeat this process as many times as you like, however there is no guarantee how much space will be freed each time if at all.