问题描述
我有一个项目，其中包含一个协议，一个实现该协议的类以及一个实现类的子类.这是我们的生产应用程序.
I've got a project which has in it a protocol, a class implementing that protocol, and a subclass of the implementation class. This is our production application.
@protocol ProductionProtocol<NSObject>
@property (nonatomic, retain) NSString *role;
@end
@interface BaseProduction : NSObject<ProductionProtocol>
NSString *role;
@end
@implementation BaseProduction
@synthesize role;
@end
@interface Production : BaseProduction
@end
@implementation Production
@end
我还获得了概念验证(POC)应用程序，该应用程序作为包含生产应用程序的单独项目实现.在POC应用程序中，我有一个扩展生产协议的协议和一个扩展生产类的类.
I've also got a proof of concept (POC) application, which is implemented as a separate project that includes the production application. In the POC application, I have a protocol that extends the production protocol, and a class that extends the production class.
@protocol POCProtocol<ProductionProtocol>
-(void)cancel;
@end
@interface POC : Production<POCProtocol>
@end
@implementation POC
-(void)cancel{...}
@end
请注意，在ProductionProtocol中，我有一个NSString角色，该角色已声明并在BaseProduction接口/类中实现.在POC中，我有一个方法"cancel"，该方法已在协议中声明，但未在接口/类中声明.
Notice that in the ProductionProtocol, I've got a role NSString which is declared, and implemented in the BaseProduction interface/class. in the POC, I've got a method 'cancel' which is declared in the protocol, but not in the interface/class.
所以这是我的问题:通过这样的类结构设置，我得到以下警告:
So here's my question: with my class structure set up like this, I get this warning:
Property 'role' requires method '-role' to be defined - use @synthesize, @dynamic or provide a method implementation
我不明白为什么收到此警告.由于综合属性位于基类中，因此POC类应该可以使用它们-快速测试似乎可以确认它们是否存在.那么，我在这里做错了什么?
I don't understand why I'm getting this warning. Since the synthesized properties are in the base class, they should be available to the POC class - and a quick test seems to confirm that they are. So what am I doing wrong here?
推荐答案
Objective-C尚无官方语言定义，但根据 Apple :
There is no official language definition for Objective-C, but according to Apple:
- 实现协议声明的方法
- 从采用协议并实现方法的类继承
但是，有报告称GCC无法识别该属性在合并的协议中，并且是在超类中实现的.您可以将编译器更改为Clang，据报告可以使用指定的方式处理此问题，也可以仅使用@dynamic告诉编译器将在运行时提供该属性的实现(在这种情况下，通过继承)来自超类).
However, reports are that GCC doesn't recognize that the property is in an incorporated protocol and is implemented in a superclass. You could change your compiler to Clang, which is reported to handle this in the specified manner, or you could just use @dynamic to tell the compiler that an implementation of the property will be provided at run time (in this case, by inheritance from the superclass).
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