Understanding the API

The API (application programming Interface, Application programming Interface) is a pre-defined function designed to provide the ability of applications and developers to access a set of routines based on a piece of software or hardware without having to access the source code. Or understand the details of the internal working mechanism. "--from Baidu Encyclopedia

Do not know how to use C language in the X-code to insert the background music, Baidu also did not be able to search to let me satisfied with the answer, so go to help know, published in the above issues I encountered. Asked for help, and in the process of chatting with a person who knows the answer, he mentions the word API.

In layman's terms, someone else has written good code or compiled programs that you can use, called APIs. You use a function, class, object in someone else's code (or program), which is called using an API.

API is like a compiled dictionary, there is nothing that can be queried through the API

It is important to note that the API does not teach you how to use functions that you have never seen before, but you can teach the functions that you can use to make better queries.

The operating system has implemented many functions for us, all of which are encapsulated into a single function, with hundreds of thousands of them, called APIs. In order for a programmer to use a feature, only the corresponding function needs to be called. Most of the common operating systems for Windows, Linux, Mac OS, and Unix are developed using the C language, and their APIs are also presented in the form of C. The number of operating system APIs is numerous, and the official must provide detailed documentation (the documentation for the Windows API is called MSDN), and programmers need to consult these documents frequently when using the API.

Summary: API everywhere, it shielded a lot of low-level details, to achieve a lot of common functions, greatly simplifying the work of programmers. Use the good API to do more!

Understanding the API