iPhone如何指定Class数据类型必须采用的协议 [英] iphone how to specify the Class data type have to adopt to a protocol

问题描述

在我的应用程序中，我需要返回类"作为返回类型，如:

In my application, I need to return the "Class" as a return type like:

Application.m:

Application.m:

+ (Class)getParserClass {
  return [NCCurrencyParser class];
}

NCCurrencyParser.m:

NCCurrencyParser.m:

@interface NCCurrencyParser NSObject <NCParser>
@protocol NCParser
  +(NSNumber *)parserNumber:(NSNumber *)number;

在调用方方法中:

Class parserClass = [Application getParserClass];
[parserClass parserNumber:1.0];

但是随后编译器给我一个错误，即parserClass可能不响应parseNumber.我如何强制Class必须采用某些协议，例如: Class< NCParser> (但不起作用)

But then the compiler gives me the error that parserClass may not respond to parseNumber. How can I force the Class have to adopt to some protocol like : Class <NCParser> (but it doesn't work)

推荐答案

Class 对象是第一类对象，并且可以实现任何其他协议Objective-C对象(id，NSObject *，...)

Class objects in Objective-C are first class objects, and can can implement protocols like any other Objective-C object (id, NSObject*, ...)

因此，只要对其他Object协议执行通常的操作即可，即:

So just do whatever you would normally do for any other Object protocol, ie:

+ (Class<NCParser>)getParserClass {
  return [NCCurrencyParser class];
}

还有

Class<NCParser> parserClass = [Application getParserClass];
[parserClass parserNumber:1.0];

在xcode 3.2.3，iPhone Simulator 4.0，GCC 4.2上构建/编译/测试

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