Comment iPhone has local security too (Score 2, Informative) 186
The Application Sandbox
For security reasons, iPhone OS restricts an application (including its preferences and data) to a unique location in the file system. This restriction is part of the security feature known as the application’s “sandbox.” The sandbox is a set of fine-grained controls limiting an application’s access to files, preferences, network resources, hardware, and so on. In iPhone OS, an application and its data reside in a secure location that no other application can access. When an application is installed, the system computes a unique opaque identifier for the application. Using a root application directory and this identifier, the system constructs a path to the application’s home directory. Thus an application’s home directory could be depicted as having the following structure:
During the installation process, the system creates the application’s home directory and several key subdirectories, configures the application sandbox, and copies the application bundle to the home directory. The use of a unique location for each application and its data simplifies backup-and-restore operations, application updates, and uninstallation. For more information about the application-specific directories created for each application and about application updates and backup-and-restore operations, see “File and Data Management.”
Important: The sandbox limits the damage an attacker can cause to other applications and to the system, but it cannot prevent attacks from happening. In other words, the sandbox does not protect your application from direct attacks by malicious entities. For example, if there is an exploitable buffer overflow in your input-handling code and you fail to validate user input, an attacker might still be able to crash your program or use it to execute the attacker’s code.
See also protections around location, camera, microphone, address book access, and network interfaces that "let users know in simple words what an application will do"