Originally called the iPhone OS, iOS is developed and distributed exclusively within Apple hardware (iPhones, iPads and iPod Touch). Similar to most operating systems, iOS is a layered OS. Applications deployed on any iOS device do not react directly with the underlying hardware, instead the operating system acts as a layer of system interfaces between those applications and the hardware; iOS is divided into four abstract layers as follows (from highest level at the top to the lowest-level at the bottom):
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Cocoa Touch layer |
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Media layer |
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Core Services layer |
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Core OS layer |
Table 1 - iOS layers
Let's look at the layers:
Cocoa Touch layer: This contains the basic framework that provides multitasking, touch-based inputs, push notifications, and most of the high level system services. This layer contains some high-level features such as app extensions, which allow sharing media content to social entities, performing simple tasks with content, photo editing, and providing shared...