Non-virtual methods in Objective-C - objective-c

Question

I need to call from the category a concrete implementation of the method (even if it's overridden). Is it possible? (Just in case: I know, all methods in Objective-C are virtual.)
// class A
#interface A
- (void)foo;
#end
#implementation A
- (void)foo
{
NSLog(#"initial foo");
}
#end
// subclass of A
#interface A1: A
#end
#implementation A1
- (void)foo
{
NSLog(#"overridden foo");
}
#end
// category to A
#interface A (Category)
- (void)bar;
#end
#impletemtation A (Category)
- (void)bar
{
[self foo]; // probably, I should specify here what exactly must be self
// but I don't know how
}
#end
/////////////////////////////////////////////////////////////////
A1 *a = [[A1 alloc] init];
[a bar]; // now the "overridden foo" string will be printed
// my goal is to print "initial foo" !!!

Answer 1

Of course, you do not have to change anything.
You can get a function pointer to the implementation of every method on a specific class:
A* receiver = …
IMP impOnA = class_getMethodImplementation( [A class], #selector( foo ));
((void (*)(id, SEL))impOnA)( receiver, #selector( foo ) ); // or whatever signature

Answer 2

You can adapt Matt Gallagher's supersequent implementation approach to find the specific method you want to invoke.
Alternatively, you could just set the class temporarily:
Class realClass = object_getClass(self);
Class fakeClass = [A class];
object_setClass(self, fakeClass);
[self foo];
object_setClass(self, realClass);
(I'm on my phone, so not 100% sure about the syntax, but the idea should work.)

Answer 3

Finally. indeed method swizzing works
#implementation A (Category)
- (void)quux
{
NSLog(#"quux");
}
- (void)bar
{
Class class = [A class];
SEL originalSelector = #selector(foo);
SEL swizzledSelector = #selector(quux);
Method originalMethod = class_getInstanceMethod(class, originalSelector);
Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
method_exchangeImplementations(originalMethod, swizzledMethod);
[self quux];
method_exchangeImplementations(originalMethod, swizzledMethod);
}
#end

Answer 4

This may solve your problem:
// class A
#interface A
- (void)foo;
#end
#implementation A
- (void)foo
{
[self fooImpl];
}
- (void)fooImpl
{
NSLog(#"initial foo");
}
#end
// subclass of A
#interface A1: A
#end
#implementation A1
- (void)foo
{
NSLog(#"overridden foo");
}
#end
// category to A
#interface A (Category)
- (void)bar;
#end
#impletemtation A (Category)
- (void)bar
{
[self fooImpl]; // probably, I should specify here what exactly must be self
// but I don't know how
}
#end
/////////////////////////////////////////////////////////////////
A1 *a = [[A1 alloc] init];
[a bar]; // now the "overridden foo" string will be printed
// my goal is to print "initial foo" !!!