iPhone OS technology layers

Almost all of the software technology today is based on modularization (which means dividing a long process into smaller parts, each representing an aspect of that process.) the reason why modularization is so popular with technology is because of many factors:

1. Each module can be tested separately and thus it becomes easier to catch errors.
2. If there is a problem in one module the other modules don’t have to be corrected.
3. Modules can be combined in multiple ways giving more options.

So, just like every other technology- iPhone Operating system is also modularized in the sense that it is made up of layers- each layer offers various functions that developers can use to build their applications. Below is a picture of the 4 functional layers of the iPhone operating system, taken from Apple’s educational website.

Let’s visit these layers in brief (as much as we can digest). The lower the layer is, the closer it is to the hardware and thus, takes care of the more fundamental parts.

Core OS & Core Services layer- when you take a picture with your iPhone, the picture is stored in your iPhone’s memory. Technically, what is happening here is this: the camera application on your iPhone takes the picture and gives it to the coreOS layer. The core OS layer stores this picture in the right place where.

Media- the media technology layer contains the functionality to support 2D, 3D, audio and video.

Cocoa Touch layer- this provides the infrastructure that all applications use- e.g., the windows, views, controls etc. It also provides the developer with user’s contact and photo information that the developer later on, uses with hardware to create applications.

The best part about this layered architecture of iPhone OS is that developers can develop apps using as many layers to get as much lower level customization as is needed. This is a very powerful feature since, this way writing simple app for iPhones doesn’t take a lot of time.