getter和setter不工作目标c

问题描述

我不能在目标c中这样做吗？

Can I not do this in objective c?

@interface Foo : NSObject {
     int apple;
     int banana;
}

@property int fruitCount;
@end

@implementation Foo
@synthesize fruitCount; //without this compiler errors when trying to access fruitCount

-(int)getFruitCount {
      return apple + banana;
}

-(void)setFruitCount:(int)value {
      apple = value / 2;
      banana = value / 2;
}

@end

我正在使用类这个：

Foo *foo = [[Foo alloc] init];
foo.fruitCount = 7;

但是我的getter和setter没有被调用。如果我改为写：

However my getter and setter's are not getting called. If I instead write:

 @property (getter=getFruitCount, setter=setFruitCount:) int fruitCount;

我的getter被调用但是setter仍然没有被调用。我缺少什么？

My getter gets called however the setter still doesn't get called. What am I missing?

推荐答案

你的语法有点偏......
定义你自己的属性实现在您的示例中使用以下内容：

Your syntax is a bit off...to define your own implementation for property accessors in your example, use the following:

@implementation Foo
@dynamic fruitCount;

-(int)fruitCount {
   return apple + banana;
}
-(void)setFruitCount:(int)value {
      apple = value / 2;
      banana = value / 2;
}

@end

使用 @synthesize 告诉编译器创建默认访问器，在这种情况下你显然不需要。 @dynamic 向编译器指示您将编写它们。以前在Apple的文档中有一个很好的例子，但它在4.0 SDK更新中以某种方式被破坏了...希望有所帮助！

Using @synthesize tells the compiler to make default accessors, which you obviously don't want in this case. @dynamic indicates to the compiler that you will write them. There used to be a good example in Apple's documentation, but it somehow got destroyed in their 4.0 SDK update... Hope that helps!

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