runtiem开源地址：https://opensource.apple.com - - -https://opensource.apple.com/tarballs/objc4/
附：查看某文件夹下包含某字符的文件---grep "file" *
class_addMethod(Person, @selector(name), (IMP)nameGetter, "@@:");
这句话的意思是：为Person类添加一个oc函数name ，实现是nameGetter，返回值和参数是第三个类型
Table 6-1 Objective-C type encodings
| Code | Meaning |
|---|---|
|
| A |
|
| An |
|
| A |
|
| A
|
|
| A |
|
| An |
|
| An |
|
| An |
|
| An |
|
| An |
|
| A |
|
| A |
|
| A C++ |
|
| A |
|
| A character string ( |
|
| An object (whether statically typed or typed |
|
| A class object ( |
|
| A method selector ( |
| [array type] | An array |
| { name=type...} | A structure |
| (name=type...) | A union |
|
| A bit field of num bits |
|
| A pointer to type |
|
| An unknown type (among other things, this code is used for function pointers) |