id

#import <Foundation/Foundation.h>

#import "Person.h"

 

 

void test(id d)

{

    

}

 

int main(int argc, const char * argv[])

{

 

    @autoreleasepool {

        Person *p = [Person new];

        //[p fsdfdsfd];

        NSObject *o = [Person new];

        // id  == NSObject *

        // 万能指针，能指向\操作任何OC对象

        id d = [Person new];

        

        [d setAge:10];

        

        [d setObj:@"321423432"];

        

        NSLog(@"%d", [d age]);

    }

    return 0;

}

#import "Person.h"

 

@implementation Person

 

@end

 

#import <Foundation/Foundation.h>

 

@interface Person : NSObject

@property int age;

@property id obj;

@end