test1

Makefile

all: test1-arc test1-no-arc
.PHONY: all

LDLIBS = -framework Foundation
CXXFLAGS = -gdwarf -std=c++11

test1-arc: test1.mm
	$(CXX) -fobjc-arc $(CXXFLAGS) $(LDLIBS) -o $@ test1.mm

test1-no-arc: test1.mm 
	$(CXX) -fno-objc-arc $(CXXFLAGS) $(LDLIBS) -o $@ test1.mm

clean:
	rm -rf test1-arc* test1-no-arc*
.PHONY: clean

test1.mm

#import <Foundation/Foundation.h>


class ObjectWrapper {
public:
  ObjectWrapper(id obj): obj_(obj) {}

  id get() { return obj_; }
  void set(id obj) { obj_ = obj; }

private:
  id obj_;
};


@interface Foo : NSObject
+ (ObjectWrapper)foo;
@end


@implementation Foo

+ (ObjectWrapper)foo {
  const char *status = (self == [Foo class]) ? "CORRECT" : "INCORRECT";
  NSLog(@"%s: receiver is %s", __func__, status);
  
  return ObjectWrapper{[[NSObject alloc] init]};
}

@end


static void callDirectly() {
  [Foo foo];
}


static void callViaInvocation() {
  SEL sel = @selector(foo);
  NSMethodSignature *sig = [Foo methodSignatureForSelector:sel];
  NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:sig];
  invocation.target = [Foo class];
  invocation.selector = sel;
  [invocation invoke];
}


int main() {
  @autoreleasepool {
    callDirectly();
    callViaInvocation();
  }
}