声明一个ObjC参数，该参数是符合协议的Class [英] Declare an ObjC parameter that's a Class conforming to a protocol

问题描述

在Objective-C中，可以将类作为参数传递给方法:

In Objective-C, it is possible to pass a class as a parameter to a method:

- (void) methodThatTakesClass:(Class)theClass;

并且可以将符合协议的实例作为参数传递:

And it is possible to pass an instance that is conforming to a protocol as a parameter:

- (void) myConformInstance:(id <MyProtocol>)theObject;

是否可以使用组合功能?一种采用符合特定协议的类的方法.

Is it possible to use the combined functionality? A method which takes a class which is conforming to a certain protocol.

推荐答案

是.以下是一个有效的程序，它将记录NSObject类.

Yes. The following is a valid program which will log the NSObject class.

#import <Foundation/Foundation.h>
void f(Class <NSObject> c) {
    NSLog(@"%@",c);
}
int main() {
    f([NSObject class]);
}

如果您尝试传递不符合NSObject的类(例如Object类)，这将导致编译器错误.您也可以将其用于方法.

This would cause a compiler error if you tried to pass a class which doesn't conform to NSObject, such as the Object class. You can also use it for methods.

- (void)printClass:(Class <NSObject>)c;

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