从其超类调用子类的方法 [英] Call subclass's method from its superclass

问题描述

我有两个类，名为 Parent 和 Child ，如下所示。 Parent 是 Child 的超类我可以使用关键字<$ c从其子类调用超类的方法$ C>超。是否可以从其超类中调用子类的方法？

I have two classes, named Parent and Child, as below. Parent is the superclass of Child I can call a method of the superclass from its subclass by using the keyword super. Is it possible to call a method of subclass from its superclass?

Child.h

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

@interface Child : Parent {

}

- (void) methodOfChild;

@end

Child.m

#import "Child.h"

@implementation Child

- (void) methodOfChild {

    NSLog(@"I'm child");

}

@end

Parent.h：

#import <Foundation/Foundation.h>

@interface Parent : NSObject {

}

- (void) methodOfParent;

@end

Parent.m：

#import "Parent.h"

@implementation Parent

- (void) methodOfParent {

    //How to call Child's methodOfChild here?

}

@end

导入 Parent.h在app delegate的.m文件头中。

Import "Parent.h" in app delegate's .m file header.

App委托的应用程序：didFinishLaunchingWithOptions： method ..

App delegate's application:didFinishLaunchingWithOptions: method..

Parent *parent = [ [Parent alloc] init];

[parent methodOfParent];

[parent release];

推荐答案

你可以像Objective C方法一样调度动态。只需用 [self methodOfChild] 调用它，这可能会生成编译器警告（你可以通过强制 self 来沉默到 id ）。

You can, as Objective C method dispatch is all dynamic. Just call it with [self methodOfChild], which will probably generate a compiler warning (which you can silence by casting self to id).

但是，为了善良的爱，不要这样做。父母应该为子女提供，而不是为父母提供子女。知道子类新方法的父是一个巨大的设计问题，在继承链上创建了错误的强耦合。如果父母需要它，为什么它不是父母的方法？

But, for the love of goodness, don't do it. Parents are supposed to provide for their children, not the children for their parents. A parent knowing about a sub-classes new methods is a huge design issue, creating a strong coupling the wrong way up the inheritance chain. If the parent needs it, why isn't it a method on the parent?

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