It does not get backed up when the device is synchronized with iTunes.Īn application can access only the files stored within its own sandbox it cannot access or create files outside of its sandbox. If the application does not clean the folder, iOS might delete them depending on when space is needed on your device. Files placed in the tmp folder are temporary and should be deleted when an application terminates. For example, results returned from a web service that you will store somewhere else later, images, etc.

This directory is where you write data that you will use temporarily during an application’s runtime. If something goes wrong with the device, files in this directory can be restored from iTunes. Data stored in this folder is backed up when the device is synchronized with iTunes. For example, you can store databases that are required by your application. This directory is where you write data that the application generates during runtime and that you want to persist between runs of the application. Preferences is handled automatically by the class NSUserDefaults and is backed up when the device is synchronized with iTunes. This directory is where any preferences are stored and where the Settings application looks for application preferences. If the user needs to restore the device, this data can be downloaded from the web server again. Data stored somewhere else – like a web server – can be placed in this directory. A major reason for not backing up cached data is that the data can be very large and extend the time it takes to synchronize your device.

However, unlike the Documents directory, it does not get backed up when the device is synchronized with iTunes. You will mostly read and write files in the Documents and tmp folder.

Further more, an application sandbox contain several folders, and you can read and write files in those listed in the table below. A sandbox holds your application’s executable file, which includes all embedded resources. A sandbox is a directory on the iOS file system. Every iOS application you create is placed in its own sandbox.

Apple sandbox system files