Changes

These operating system layers can be presented diagrammatically as illustrated in Figure 3-1:

[[Image:iPhoneOSArchitecture.png|The iOS 5 SDK Architecture Diagram]]

Some diagrams designed to graphically depict the iOS software stack show an additional box positioned above the Cocoa Touch layer to indicate the applications running on the device. In the above diagram we have not done so since this would suggest that the only interface available to the app is Cocoa Touch. In practice, an app can directly call down any of the layers of the stack to perform tasks on the physical device.