将基类指针指向目标c中的派生类 [英] Assiging base class pointer to derived class in objective c

问题描述

我有一个名为ModelBase的基类，还有一个名为"Person"的派生类.现在，在person的init方法中，我有类似的东西

I have a base class called ModelBase and I have a derived class called "Person". Now in the init method of person, I have something like

-(Person*) init {
     if(self = [super init])
         return self;

     return nil; 
}

但是，目标C抱怨说初始化"struct ModelBase *"，预期"struct Person *"的不兼容的Objective-C类型.我只用[super init]初始化self，这是初始化指向派生类的基类指针.

However, Objective C complains that Incompatible Objective-C types initializing 'struct ModelBase *', expected 'struct Person *'. I'm only initializing self with [super init] which is initializing a base class pointer to a derived class.

我想念什么?

推荐答案

您是否声明了要返回的ModelBase初始化方法(ModelBase *)?如果是这样，请将其更改为返回(id).您会注意到，可可中的大多数初始化器都是出于这个原因而返回(id).

Did you declare your ModelBase init method to return (ModelBase*) ? If so, change it to return (id) instead. You'll notice that most initializers in Cocoa return (id) for this very reason.

代替

- (ModelBase*)init;

您想要的

- (id)init;

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