创建父类ClassA，子类ClassB继承ClassA

ClassA.h

#import <Foundation/Foundation.h>
@interface ClassA : NSObject
- (void)method:(int)count;

@end

ClassA.m

#import "ClassA.h"
@implementation ClassA

- (void)method:(int)count
{  
    NSLog(@"%d",count);
}

@end

main.m

#import <Foundation/Foundation.h>
#import "ClassB.h"
#import "ClassA.h"

int main(int argc, const char *argv[])
{
  @autoreleasepool
  {
    /*_______________________________对象与类的关系________________________*/

    //构建类名
    Class className = NSClassFromString(@"ClassA");
    Class className2 = [ClassA class];

    //1.查看某个对象是否是某个类的对象
    ClassB *b = [[ClassB alloc]init];
    BOOL isYes1 = [b isMemberOfClass:[ClassB class]];
    BOOL isYes2 = [b isMemberOfClass:[ClassA class]];

    NSLog(@"b %@ ClassB 的对象",isYes1?@"是":@"不是")；
    NSLog(@"b %@ ClassA的对象",isYes2?@"是":@"不是")；

    //查看某个对象是否是某个类的派生对象 -> b是否是B的或B的父类的对象
    BOOL isYes3 = [b isKindOfClass:[ClassB class]];
    BOOL isYes4 = [b isKindOfClass:[ClassA class]];

    NSLog(@"b %@ ClassB的派生对象",isYes3?@"是":@"不是")；
    NSLog(@"b %@ ClassA的派生对象",isYes4?@"是":@"不是")；

    /*+____________对象间的关系____________________________________________*/

    NSObject *objc1 = [[NSObject alloc]init];
    NSObject *objc2 = [[NSObject alloc]init];

    NSLog(@"%p %p",string1,string2);

    BOOL isEqualString = [string1 isEqualTostring:string2];

    NSLog(@"两个字符串内容%@",isEqualString?@"相同":@"不同")；

    /*_______________________对象与方法____________________________________*/
    [b method:10];
    //判断某个对象是否响应某方法 --> 对象是否能调用该方法

    //1.
    SEL sel = @selector(method:);
    BOOL isTrue = [b respondsToSelector:sel];

    //2.
    BOOL isTrue1 = [b respondsToSelector:@selector(method:)];
  
    NSLog(@"对象 b  %@ 方法 method",isTrue1?@"响应":@"不响应")；
  }
  return 0;
}