IOS Development Notes 1-switch to a new company to understand the responsibilities of each department

1. analogy

When you are a beginner in Ios development, you should first understand the environment in which the developed applications are stored. Just like switching to a company as a code farmer, you must first understand the various departments of the company so that you can find out which department to look for in the future. The environment in which Ios applications survive is the Ios operating system. The system architecture of iOS is divided into four layers: Core OS layer, Core Services layer, and Media layer) and Cocoa Touch layer, such:

2. Core OS-Senior Management

The underlying layer of the iOS system architecture is the core operating system layer, which includes memory management, file system, power management, and some other operating system tasks. It can directly interact with hardware devices. The iPhone OS provides many interface sets for accessing low-level features of the operating system. iPhone applications access these functions through the LibSystem library. These functions are provided through C language APIs. Like the company's senior management, commands are issued from here to develop the company's development strategy, to help the company find money, to take charge of the company's major external cooperation, and internal organization. As the core of a product department, you do not need to contact these people under normal circumstances, but you still have the opportunity to contact them through some channels. Under normal circumstances, App development does not directly deal with these issues, but they also provide some interface sets for normal calls. But it is better not to deal with them directly. The way of thinking is different (they are C thinking, we are Object-C ).

3. Core Service-Finance Department

To join a company, one is money, the other is development, and the development is still too weak. So it is more about money. There is no way to survive. Of course, the more you give, the better. Core Services provides richer functions based on Core OS, including Foundation. framework and Core Foundation. framework is called Foundation because it provides a series of basic functions to process strings, arrange, combine, calendar, and time. foundation is an API of Objective-C, and Core Fundation is an API of C. Foundation. framework is a basic Framework that we use in the process of App development. It is like the result of our work is still converted to salary. Every month, we are waiting to pay for the Foundation. framework is used for App development.

4. Media-Personnel Department

We can use various media files in the application to record audio and video, draw images, and create basic animation effects. It includes the following components: Core Audio, OpenGL, Audio MixingAudio Recording, Video Playback, JPG, PNG, TIFFPDF, Quartz, Core Animation, OpenGL ES... when we have some daily questions, such as how the company pays social security and the Provident Fund, we should ask the personnel department. Of course, you should raise your salary, contact the personnel department.

5. Cocoa Touch-Development Department

Most of our work is with our colleagues in the Development Department. This layer provides a variety of useful frameworks for our application development, and most of them are related to the user interface. In essence, it is responsible for the user's touch interaction operations on iOS devices. It is an Objective-c api, the core of which is UIKit. framework, a variety of components on the application interface, all provided by it, in addition to it is responsible for processing the screen multi-point touch events, text output, pictures, webpage display, access to cameras or files, and accelerated sensing. We are engaged in Ios development. Most of our work is to implement various interactions or Ui interfaces.

Summary:When developing the iPhone program, we should first start from the upper layer and use the Objective-C encapsulated library, that is, through UIKit. framework and Foundation. framework for Development, and when faced with some complex functions, such as multimedia processing or drawing, and then find the relevant framwork on the lower layer.