The iOS operating system isolates each and every app on the system. Apps are not allowed to view or modify each other's data, business logic, and so on. Isolation prevents one app from knowing whether any other app is present on the system or whether apps can access the iOS operating system kernel until the device is jailbroken. This ensures a high degree of separation between the app and operating system.
iOS provides two types of isolation:
Process isolation
Filesystem isolation
In process isolation, it is not possible for a random app to read another's memory region. Inter-app communication is restricted; there are no IPCs available for any process to communicate with another process.
All apps run in their own sandboxes. Apps are isolated not only from other apps but also from the operating system. By default, all apps on a device which is not jailbroken will be running as user mobile; the XNU kernel (similar to the Android Linux kernel) has a sandbox extension...
