How to use NSInvocation to call a class method? [closed]

Question

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.

Closed 9 years ago.

I've a class method which is not declared in the h file, but implemented in the m file. now I want to call it in another class, since the return value is a int, I can't use selector directly, so I use NSInvocation.

below is what i'm doing:

SEL selector = ***;
NSMethodSignature *signature = [classA methodSignatureForSelector:selector];
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
invocation.selector = selector;
invocation.target = [classA class];
[invocation setArgument:(void *)arg atIndex:2];
[invocation invoke];

the invoke doesn't succeed, Why?

Answer 1

When passing the arguments, you pass their address, not their value. Try the following:

[invocation setArgument:&arg
                atIndex:2];

See [NSInvocation setArgument:atIndex:] in the class reference.