// 给MJPerson类添加分类
@interface MJPerson : NSObject
- (void)run;
@end@implementation MJPerson
- (void)abc{}
- (void)run{NSLog(@"MJPerson - run");}
+ (void)run2{}
@end// MJPerson的分类,给MJPerson添加test方法
@interface MJPerson (Test)
- (void)test;
@end @implementation MJPerson (Test)
- (void)run{ NSLog(@"MJPerson (Test) - run");}
- (void)test{ NSLog(@"test");} // 会存放在类对象中
+ (void)test2 {} // 会存放在元类对象中
@end// 调用拓展出来的方法
MJPerson *person = [[MJPerson alloc] init];
[person run];
[person test];

@interface MJPerson (Test)
// 各类中添加属性
@property (assign, nonatomic) int weight;
// 只会生成方法的声明
//- (void)setWeight:(int)weight;
//- (int)weight;
@end// 实现get set方法 来使得分类中的方法可以赋值和访问
#define MJKey [NSString stringWithFormat:@"%p", self]
@implementation MJPerson (Test)NSMutableDictionary *names_;
NSMutableDictionary *weights_;
+ (void)load
{weights_ = [NSMutableDictionary dictionary];names_ = [NSMutableDictionary dictionary];
}- (void)setName:(NSString *)name { names_[MJKey] = name; }
- (NSString *)name { return names_[MJKey]; }- (void)setWeight:(int)weight { weights_[MJKey] = @(weight); }- (int)weight{ return [weights_[MJKey] intValue]; }

#import "MJPerson.h"
@interface MJPerson (Test)
@property (copy, nonatomic) NSString *name;
@property (assign, nonatomic) int weight;
@end#import "MJPerson+Test.h"
#import <objc/runtime.h>@implementation MJPerson (Test)
- (void)setName:(NSString *)name
{objc_setAssociatedObject(self, @selector(name), name, OBJC_ASSOCIATION_COPY_NONATOMIC);
}- (NSString *)name
{// 隐式参数// _cmd == @selector(name)   只有get方法才可以这么写return objc_getAssociatedObject(self, _cmd);
}- (void)setWeight:(int)weight
{objc_setAssociatedObject(self, @selector(weight), @(weight), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}- (int)weight
{// _cmd == @selector(weight)return [objc_getAssociatedObject(self, _cmd) intValue];
}// 这样就可以像调用类属性一样来调用分类里面的属性
person.name = "Lewis"

// 格式
返回值 (^block)(参数) = ^{ block的内容 }// 例子
void (^block)(void) = ^{ NSLog(@"this is a block") }
// 调用
block()

<1>. 捕获局部auto类型变量（自动变量：离开作用域就会自动销毁）
<2>. 也可以捕获局部static类型变量
// 默认定义的局部变量，默认就是auto
// auto int age = 10
int age = 10    // 传递是age的值
static int height = 10   // 传递的是height的地址值
// 在创建这个block对象的时候，age和height的值已经存储到了block的内存中
void (^block)(void) = ^{// age和height的值已经被捕获进来了NSLog(@"age is %d, height is %d", age, height);
};
age = 20;
height = 20;
// 通过*height取出height的值，只是通过指针取出指向的外部的值
block(); // 输出：age is 10, height is 20

int a = 10;// 堆：动态分配内存,需要程序员申请申请，也需要程序员自己管理内存
void (^block1)(void) = ^{NSLog(@"Hello");
};
int age = 10;
void (^block2)(void) = ^{NSLog(@"Hello - %d", age);
};NSLog(@"%@ %@ %@", [block1 class], [block2 class], [^{NSLog(@"%d", age);
} class]);// 输出：__NSGlobalBlock__ __NSMallocBlock__ __NSStackBlock__

void (^block)(void);
void test2()
{// NSStackBlockint age = 10;block = [^{NSLog(@"block---------%d", age);} copy];// copy操作之后 block就会在堆上，就会变成NSMallocBlock// 如果没有copy操作，那么这个block捕获的是auto变量，所以是一个NSStackBlock，所以在作用域之外调用，打印出的age值不会是10，因为这个age已被释放[block release];
}void test()
{// Global：没有访问auto变量void (^block1)(void) = ^{NSLog(@"block1---------");};// Stack：访问了auto变量int age = 10;void (^block2)(void) = ^{NSLog(@"block2---------%d", age);};NSLog(@"%p", [block2 copy]);//    NSLog(@"%@ %@", [block1 class], [block2 class]);
}int age = 10;int main(int argc, const char * argv[]) {@autoreleasepool {int a = 10;NSLog(@"数据段：age %p", &age);NSLog(@"栈：a %p", &a);NSLog(@"堆：obj %p", [[NSObject alloc] init]);NSLog(@"数据段：class %p", [MJPerson class]);}return 0;
}