说明：  两个比较好的brew文档，初学者最好的学习资料。学习brew最重要的是对API和程序流程的熟悉，不要拘泥于某个宏或者函数指针的理解，要做到先上手，再贯通理解。
(Good brew two documents, the best learning materials for beginners. Learning brew is the most important API familiar with the processes and procedures, do not rigidly adhere to a macro or a function pointer of understanding, to be started first, and then through understanding.)