Sign Up to our social questions and Answers Engine to ask questions, answer people’s questions, and connect with other people.
Login to our social questions & Answers Engine to ask questions answer people’s questions & connect with other people.
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
@interface Foo : NSObject {
}
- (Bar)bar;
At runtime, given [Foo class], how do we find out the return type of all methods Foo has?
I have been studying the Objective-C runtime API for a while now; as far as I could tell, there is no way to get the return type (i.e. Class) of a method or a property. This seems to be a serious omission in any reflection API.
You can tell basic information like what C type it is, but you can’t differentiate between various instance types (or classes) on the return type.
Objective-C was never designed nor intended to have that level of a reflection. Mostly because doing so would massively increase the size of the executables (all the metadata) and supporting full argument/return-type metadata introspection for all C types — think C++ types — would be incredibly complex.
Already, there have been cases where the metadata related to the parameterization of methods has measured in the orders of magnitude larger than the generated code when passing C++ objects to Objective-C methods (literally — MBs for the metadata for a single method call).
An example of a relatively simple type in argument/return-type metadata form:
And a particularly egregious example from the WebKit: