objective-c - 子类化和 "promote"对象

Question

我有一个类:

BasicObject : NSObject

AdvObject : BasicObject

在其他类中，我通过以下方式创建实例:

BasicObject *bObj = [[BasicObject alloc] initWithSomething:propertyOne andSomethingElse:propertyTwo];

BasicObject 有两个属性:

@interface BasicObject : NSObject

-(id)initWithSomething:propertyOne andSomethingElse:propertyTwo;

@property (strong,nonatomic) NSString* propertyOne;
@property (strong,nonatomic) NSArray* propertyTwo;

然后在初始化器中:

-(id)initWithSomething:propertyOne andSomethingElse:propertyTwo
{
    if (self = [super init])
    {
        _propertyOne = propertyOne;
        _propertyTwo = propertyTwo;

        if(!propertyTwo) //this is not valid condition i know, not important here
          {
             AdvObject *aObj = [[AdvObject alloc] initWithBasic:self]; //here it what i'm more concern about
             return aObj;
          }
    }

    return self;
}

所以在初始化器的 AdvObject 类中我有:

@implementation AdvObject

@synthesize basics = _basics;


-(id)initWithBasic:(BasicObject *)bObj
{
    if(self = [super init]) {
        _basics = bObj;
    }

    return self;
}

然后当我返回这个对象时，我当然有一个 object.basics 正确填充，但为什么我不能访问 object.propertyOne？ (这是零)。我做错了什么？这是正确的设计吗？

Answer 1

或者，您可以避免整个模式过于聪明，并创建一个类工厂方法，根据传递的参数返回 BasicObject 或 AdvObject