objective-c 获取seletor方法的返回类型
If this is runtime discovery of the return type, you can use the ObjC runtime API to lookup the method definition, then return type, of a given object method. Specifically the methods:
Method class_getInstanceMethod(Class aClass, SEL aSelector)
or
Method class_getClassMethod(Class aClass, SEL aSelector)
will get you a Method
struct, which you can subsequently query with
void method_getReturnType(Method method, char *dst, size_t dst_len)
to get the cstring description of the return type. This description is not quite human readable - for instance, given your example, you would want to check if the string referenced in *dst
is equal to "@". If it is, then the return type is of type id
. You can see a reference to the different type encodings here, and the ObjC runtime API methods I mentioned here.
As mentioned by H2C03, the objc_msgSend_fpret
and objc_msgSend_stret
variants should be used when the return type inferred from method_getReturnType
indicates their use is appropriate (eg, when the return type would be a struct or float. See the documentation notes on those two methods on the ObjC Runtime API docs page.)
Also, because I want you to have a good day, I feel like I should warn you about runtime code discovery typically being a bit brittle and usually a nasty performance smell. Anyways. :)
http://stackoverflow.com/questions/11285780/objective-c-objc-msgsend-return-type
posted on 2012-08-22 00:00 kiao295338444 阅读(346) 评论(0) 编辑 收藏 举报