如何在协议中定义和实现属性 [英] How to define and implement properties in protocol

问题描述

我想定义一个具有少量属性的协议，并需要在另一个NSObject子类中使用这些属性。请给我链接或示例代码。我需要使用10.5。

I want to define one protocol with few properties and need to use those properties in another NSObject subclass. Please give me link or example code. I need that to work with 10.5.

感谢
请检查以下样本代码

Thanks PLEASE CHECK THE FOLLOWING SAMPLE CODE

@protocol MyProtocol
@property (nonatomic, readonly) id someObject;
@property (nonatomic, getter=isAlive) BOOL alive;
@end

#import "MyProtocol.h"
@interface MyCustomClass : NSObject <MyProtocol>{

}
@end

#import "MyCustomClass.h"
@implementation MyCustomClass
@synthesize someObject,alive;

/*
- (id)someObject {
    return nil;
}

- (BOOL)isAlive {
    return YES;
}

- (void)setAlive:(BOOL)aBOOL {
}
*/
@end

**已添加：
使用x86_64架构的补充代码可以正常工作。但错误，如果我将改变架构到i386，然后我得到以下警告：

**Added: Compling code with x86_64 architecture works fine. But error if i'll change the architecture to i386, then i am getting following warnings:

MyCustomClass.m:13: error: synthesized property 'someObject' must either be named the same as a compatible ivar or must explicitly name an ivar

 error: synthesized property 'alive' must either be named the same as a compatible ivar or must explicitly name an ivar

我只是想知道为什么它在x86_64中使用@synthesize而不是在i386 。**

I just want to know why it is working in x86_64 with @synthesize and not in i386.**

推荐答案

@property 类需要定义匹配该属性的方法。

@property just says to the compiler that the class is expected to define the methods to match that property.

@protocol MyProtocol
@property (nonatomic, readonly) id someObject;
@property (nonatomic, getter=isAlive) BOOL alive;
@end

实施该协议的任何内容现在需要具有

Anything implementing that protocol will now need to have

- (id)someObject;
- (BOOL)isAlive;
- (void)setAlive:(BOOL)aBOOL;

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