ChildClass.h

#import <Foundation/Foundation.h>
#import "MyClass.h"

@interface ChildClass : MyClass
@end

ChildClass.m

#import "ChildClass.h"

@implementation ChildClass
- (void)method
{
    NSLog(@"Hello ChildClass!");
}
@end

main.m

#import <Foundation/Foundation.h>
#import "MyClass.h"
#import "ChildClass.h"

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        MyClass *myclass = [[MyClass alloc]init];
        [myclass callMyClassSelfMethod]; //Hello MyClass!
        [myclass callMyClassSuperMethod]; //Hello ParentClass!
        ChildClass *childclass = [[ChildClass alloc]init];
        [childclass callMyClassSelfMethod]; //Hello ChildClass!
        [childclass callMyClassSuperMethod]; //Hello ParentClass!
    }
    return 0;
}

MyClass.h

#import <Foundation/Foundation.h>
#import "ParentClass.h"

@interface MyClass : ParentClass
- (void)callMyClassSelfMethod;
- (void)callMyClassSuperMethod;
@end

MyClass.m

#import "MyClass.h"

@implementation MyClass
- (void)method
{
    NSLog(@"Hello MyClass!");
}
- (void)callMyClassSelfMethod
{
    [self method];
}
- (void)callMyClassSuperMethod
{
    [super method];
}
@end

ParentClass.h

#import <Foundation/Foundation.h>

@interface ParentClass : NSObject
- (void)method;
@end

ParentClass.m

#import "ParentClass.h"

@implementation ParentClass
- (void)method
{
    NSLog(@"Hello ParentClass!");
}
@end