声明委托人遵守其他协议 [英] Declare that delegate conforms to another protocol

问题描述

在Objective-C中，是否可以在第二个委托协议定义中包括与委托协议的一致性？我正在尝试避免这样的模式：

In Objective-C, is it possible to include conformance to a delegate protocol inside a second delegate protocol definition? I'm trying to avoid a pattern like this:

    if ([objectA conformsToProtocol:@protocol(privateDelegateProtocol)])
    {
        id<privateDelegateProtocol> privateDelegate = (id<privateDelegateProtocol>)objectA;
        objectB.privateDelegate = privateDelegate;
    }

我已经知道 objectA 符合我自己的委托协议 @protocol（myDelegateProtocol），因为实际上 self.myDelegate = objectA 。如果我可以在该协议定义中以某种方式指定它还必须符合 @protocol（privateDelegateProtocol），那么我可以这样写：

I already know that objectA conforms to my own delegate protocol @protocol(myDelegateProtocol), because in fact self.myDelegate = objectA. If I could somehow specify in that protocol definition that it must also conform to @protocol(privateDelegateProtocol), then I could just write:

objectB.privateDelegate = self.myDelegate;

这似乎更简单，更优雅。如果协议方法未实现，我宁愿收到编译时警告，而不必在运行时进行检查。有办法吗？

which seems much simpler and more elegant. I'd much rather get a compile time warning if the protocol methods are not implemented, rather than have to check for that at runtime. Is there a way?

推荐答案

协议可以像类一样从协议继承。

Protocols can inherit from protocols the same way classes do.

@protocol myDelegateProtocol <NSObject, privateDelegateProtocol>
...
@end

任何符合该协议的对象都必须还符合NSObject和privateDelegateProtocol协议。

Any object that conforms to that protocol must also conform to the NSObject and privateDelegateProtocol protocols.

您还可以指定您的委托人必须同时遵守这两个协议，而不要求所有符合myDelegateProtocol的对象也必须遵守privateDelegateProtocol。

You can also specify that your delegate must conform to both protocols without requiring all objects that conform to myDelegateProtocol also conform to privateDelegateProtocol.

@property (nonatomic, weak) id<myDelegateProtocol, privateDelegateProtocol> delegate;

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