协议练习改成block

#import <Foundation/Foundation.h>
@interface Person : NSObject

@property (nonatomic, copy) void (^brak)(void); //声明void类返回void的block类型的brak,
@property (nonatomic, copy) void (^tail)(void);   //@property同时声明变量
@property (nonatomic, copy) void (^run)(void);
- (void)playwithanimal;                                     //一个实例方法
@end

#import "Person.h"

@implementation Person

- (void)playwithanimal               //编写方法
{
    if(_brak)                       //如果_brak对像飞空,则_brak(),这_brak就是^block声明的方法
        _brak();
    if(_tail)
        _tail();
    if(_run)
        _run();
  
 
}

@end

#import "ViewController.h"
#import "Person.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    Person * person = [[Person alloc]init];    //person类中声明一个对象并初始化分配内存空间.
    person.brak = ^{                           //person指向brak的地址.block返回void,打印出字符
        NSLog(@"wang wang");                   //但是有个缺点,就是同样的brak,结果内容只能是一样的wangwang;
                                               //如果通过协议,可以通过两个其他类而得到一个事例一样的方法中,实行的结果不一样
    };
    
    person.tail = ^{
        NSLog(@"roking tail");
    };
    person.run = ^{
        NSLog(@"the animal is running");
    };
    [person playwithanimal];                      //调用方法playwithanimal,则会运行其中的block,block返回
    
                                                               //中则会打印相关内容


}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end