block捕获

- (void)viewDidLoad {

    [super viewDidLoad];

    auto int a = 5;//自动变量:过作用域就销毁(值传递)

    static int b = 5;//静态变量(指针传递)

    //block会对局部变量进行捕获、全局变量不会捕获

    self.block = ^() {

        NSLog(@"a=%d b=%d",a,b);

    };

    a = 20;

    b = 20;

    self.block();

}

2018-06-02 16:58:57.752234+0800 testaaa[7833:742834] a=5 b=20

#import "person.h"

@implementation person

-(void)log

{

    //默认传入

    //void eat (person * self,SEL _cmd) {

    // }

    //参数是局部变量，依然会被捕获

    void(^block)(void) = ^{

        //self为局部变量

        NSLog(@"%@",self);

        //_name的本质是self->_name

        NSLog(@"%@",_name);

    };

    block();

}

void eat (person * self,SEL _cmd) {

}

@end