each iOS app has its own app sandbox, which is the file system directory, isolated from other apps ' file systems,and theiOS system doesn't allow access to the app sandbox for other apps. Access is already open in iOS8.
The application sandbox typically includes the following file directories: Application packages,documents,libaray(below Caches and Preferences directories),tmp. 1. Documents: Apple recommends that the file data that is created in the program or browsed in the program be kept in this directory, which is included in itunes Backup and restore. 2,libaray/caches: Store cache files,iTunes will not back up this directory, this directory files will not be deleted in the app exit. General storage volume is relatively large, not particularly important resources. 3.libaray/preferences: Save all your app's preferences,iOS Settings The app will find the app's settings in that directory, andiTunes will automatically back it up. 4. tmp: Save the temporary data required for the application to run, and then delete the corresponding files from the directory when you have finished using them. When the app is not running, the system may also clear files in that directory, andiTunes will not sync the directory. when the iphone restarts , the files in that directory are lost.
Sandbox (sandbox)
