『iOS』各种不同情况下block相关的源码表现

这篇文章主要记录下，block在不同情况下的源码表现，目的在于加深自己对于block理解

相关命令

xcrun  -sdk  iphoneos  clang  -arch  arm64  -rewrite-objc  OC源文件  -o  输出的CPP文件
__weak无法生成源码的问题
clang -rewrite-objc -fobjc-arc -fobjc-runtime=macosx-10.14 main.m -o main1.cpp

1.

void (^block)(void);

void test()
{
    int age = 10;
    static int height = 10;
    
    block = ^{
        // age的值捕获进来（capture）
        NSLog(@"age is %d, height is %d", age, height);
    };
    
    age = 20;
    height = 20;
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        test();
        block();
    }
    return 0;
}

源码

void (*block)(void);


struct __test_block_impl_0 {
  struct __block_impl impl;
  struct __test_block_desc_0* Desc;
  int age;
  int *height;
  __test_block_impl_0(void *fp, struct __test_block_desc_0 *desc, int _age, int *_height, int flags=0) : age(_age), height(_height) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};
static void __test_block_func_0(struct __test_block_impl_0 *__cself) {
  int age = __cself->age; // bound by copy
  int *height = __cself->height; // bound by copy


        NSLog((NSString *)&__NSConstantStringImpl__var_folders_2r__m13fp2x2n9dvlr8d68yry500000gn_T_main_d2875b_mi_0, age, (*height));
    }

static struct __test_block_desc_0 {
  size_t reserved;
  size_t Block_size;
} __test_block_desc_0_DATA = { 0, sizeof(struct __test_block_impl_0)};
void test()
{
    int age = 10;
    static int height = 10;

    block = ((void (*)())&__test_block_impl_0((void *)__test_block_func_0, &__test_block_desc_0_DATA, age, &height));

    age = 20;
    height = 20;
}

int main(int argc, const char * argv[]) {
    /* @autoreleasepool */ { __AtAutoreleasePool __autoreleasepool; 
        test();
        ((void (*)(__block_impl *))((__block_impl *)block)->FuncPtr)((__block_impl *)block);
    }
    return 0;
}

2.

void (^block)(void);

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

        void (^block)(void) = ^{
            NSLog(@"Hello, World!");
        };

        block();
    }
    return 0;
}

源码

struct __block_impl {
    void *isa;
    int Flags;
    int Reserved;
    void *FuncPtr;
};

struct __main_block_impl_0 {
  struct __block_impl impl;
  struct __main_block_desc_0* Desc;
  // 构造函数（类似于OC的init方法），返回结构体对象
  __main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, int flags=0) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};

// 封装了block执行逻辑的函数
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {

            NSLog((NSString *)&__NSConstantStringImpl__var_folders_2r__m13fp2x2n9dvlr8d68yry500000gn_T_main_c60393_mi_0);
        }

static struct __main_block_desc_0 {
  size_t reserved;
  size_t Block_size;
} __main_block_desc_0_DATA = { 0, sizeof(struct __main_block_impl_0)};
int main(int argc, const char * argv[]) {
    /* @autoreleasepool */ { __AtAutoreleasePool __autoreleasepool;
        // 定义block变量
        void (*block)(void) = &__main_block_impl_0(
                                                   __main_block_func_0,
                                                   &__main_block_desc_0_DATA
                                                   );

        // 执行block内部的代码
        block->FuncPtr(block);
    }
    return 0;
}

3.

@implementation Person

int age_ = 10;

- (void)test
{
    void (^block)(void) = ^{
        NSLog(@"-------%d", [self name]);
    };
    block();
}

- (instancetype)initWithName:(NSString *)name
{
    if (self = [super init]) {
        self.name = name;
    }
    return self;
}

@end

源码

struct __MJPerson__test_block_impl_0 {
  struct __block_impl impl;
  struct __MJPerson__test_block_desc_0* Desc;
  MJPerson *self;
  __MJPerson__test_block_impl_0(void *fp, struct __MJPerson__test_block_desc_0 *desc, MJPerson *_self, int flags=0) : self(_self) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};
static void __MJPerson__test_block_func_0(struct __MJPerson__test_block_impl_0 *__cself) {
  MJPerson *self = __cself->self; // bound by copy

        NSLog((NSString *)&__NSConstantStringImpl__var_folders_2r__m13fp2x2n9dvlr8d68yry500000gn_T_MJPerson_1027e6_mi_0, ((NSString *(*)(id, SEL))(void *)objc_msgSend)((id)self, sel_registerName("name")));
    }
static void __MJPerson__test_block_copy_0(struct __MJPerson__test_block_impl_0*dst, struct __MJPerson__test_block_impl_0*src) {_Block_object_assign((void*)&dst->self, (void*)src->self, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static void __MJPerson__test_block_dispose_0(struct __MJPerson__test_block_impl_0*src) {_Block_object_dispose((void*)src->self, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static struct __MJPerson__test_block_desc_0 {
  size_t reserved;
  size_t Block_size;
  void (*copy)(struct __MJPerson__test_block_impl_0*, struct __MJPerson__test_block_impl_0*);
  void (*dispose)(struct __MJPerson__test_block_impl_0*);
} __MJPerson__test_block_desc_0_DATA = { 0, sizeof(struct __MJPerson__test_block_impl_0), __MJPerson__test_block_copy_0, __MJPerson__test_block_dispose_0};

static void _I_MJPerson_test(MJPerson * self, SEL _cmd) {
    void (*block)(void) = ((void (*)())&__MJPerson__test_block_impl_0((void *)__MJPerson__test_block_func_0, &__MJPerson__test_block_desc_0_DATA, self, 570425344));
    ((void (*)(__block_impl *))((__block_impl *)block)->FuncPtr)((__block_impl *)block);
}


static instancetype _I_MJPerson_initWithName_(MJPerson * self, SEL _cmd, NSString *name) {
    if (self = ((MJPerson *(*)(__rw_objc_super *, SEL))(void *)objc_msgSendSuper)((__rw_objc_super){(id)self, (id)class_getSuperclass(objc_getClass("MJPerson"))}, sel_registerName("init"))) {
        ((void (*)(id, SEL, NSString *))(void *)objc_msgSend)((id)self, sel_registerName("setName:"), (NSString *)name);
    }
    return self;
}

4.


typedef void (^MJBlock)(void);

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

        MJBlock block;

        {
            MJPerson *person = [[MJPerson alloc] init];
            person.age = 10;
            int age = 10;
            block = ^{
                NSLog(@"---------%d", person.age);
            };
        }

        NSLog(@"------");
    }
    return 0;
}

源码


typedef void (*MJBlock)(void);


struct __main_block_impl_0 {
  struct __block_impl impl;
  struct __main_block_desc_0* Desc;
  MJPerson *__strong person;
  __main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, MJPerson *__strong _person, int flags=0) : person(_person) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
  MJPerson *__strong person = __cself->person; // bound by copy

                NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_13ee9c_mi_0, ((int (*)(id, SEL))(void *)objc_msgSend)((id)person, sel_registerName("age")));
            }
static void __main_block_copy_0(struct __main_block_impl_0*dst, struct __main_block_impl_0*src) {_Block_object_assign((void*)&dst->person, (void*)src->person, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static void __main_block_dispose_0(struct __main_block_impl_0*src) {_Block_object_dispose((void*)src->person, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static struct __main_block_desc_0 {
  size_t reserved;
  size_t Block_size;
  void (*copy)(struct __main_block_impl_0*, struct __main_block_impl_0*);
  void (*dispose)(struct __main_block_impl_0*);
} __main_block_desc_0_DATA = { 0, sizeof(struct __main_block_impl_0), __main_block_copy_0, __main_block_dispose_0};
int main(int argc, const char * argv[]) {
    /* @autoreleasepool */ { __AtAutoreleasePool __autoreleasepool; 
        MJBlock block;

        {
            MJPerson *person = ((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)objc_getClass("MJPerson"), sel_registerName("alloc")), sel_registerName("init"));
            ((void (*)(id, SEL, int))(void *)objc_msgSend)((id)person, sel_registerName("setAge:"), 10);


            int age = 10;
            block = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA, person, 570425344));
        }

        NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_13ee9c_mi_1);
    }
    return 0;
}

5.

typedef void (^MJBlock)(void);

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        MJBlock block;

        {
            MJPerson *person = [[MJPerson alloc] init];
            person.age = 10;

            __weak MJPerson *weakPerson = person;
            int age = 10;
            block = ^{
                NSLog(@"---------%d", weakPerson.age);
            };
        }

        NSLog(@"------");
    }
    return 0;
}

源码

typedef void (*MJBlock)(void);


struct __main_block_impl_0 {
  struct __block_impl impl;
  struct __main_block_desc_0* Desc;
  MJPerson *__weak weakPerson;
  __main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, MJPerson *__weak _weakPerson, int flags=0) : weakPerson(_weakPerson) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
  MJPerson *__weak weakPerson = __cself->weakPerson; // bound by copy

                NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_1cad2d_mi_0, ((int (*)(id, SEL))(void *)objc_msgSend)((id)weakPerson, sel_registerName("age")));
            }
static void __main_block_copy_0(struct __main_block_impl_0*dst, struct __main_block_impl_0*src) {_Block_object_assign((void*)&dst->weakPerson, (void*)src->weakPerson, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static void __main_block_dispose_0(struct __main_block_impl_0*src) {_Block_object_dispose((void*)src->weakPerson, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static struct __main_block_desc_0 {
  size_t reserved;
  size_t Block_size;
  void (*copy)(struct __main_block_impl_0*, struct __main_block_impl_0*);
  void (*dispose)(struct __main_block_impl_0*);
} __main_block_desc_0_DATA = { 0, sizeof(struct __main_block_impl_0), __main_block_copy_0, __main_block_dispose_0};
int main(int argc, const char * argv[]) {
    /* @autoreleasepool */ { __AtAutoreleasePool __autoreleasepool; 
        MJBlock block;

        {
            MJPerson *person = ((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)objc_getClass("MJPerson"), sel_registerName("alloc")), sel_registerName("init"));
            ((void (*)(id, SEL, int))(void *)objc_msgSend)((id)person, sel_registerName("setAge:"), 10);

            __attribute__((objc_ownership(weak))) MJPerson *weakPerson = person;
            int age = 10;
            block = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA, weakPerson, 570425344));
        }

        NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_1cad2d_mi_1);
    }
    return 0;
}

6.


typedef void (^MJBlock)(void);

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        MJBlock block;

        {
            MJPerson *person = [[MJPerson alloc] init];
            person.age = 10;

            __weak MJPerson *weakPerson = person;
            block = ^{
                __strong MJPerson *strongPerson =weakPerson;
                NSLog(@"---------%d", strongPerson.age);
            };
        }

        NSLog(@"------");
    }
    return 0;
}

源码

typedef void (*MJBlock)(void);


struct __main_block_impl_0 {
  struct __block_impl impl;
  struct __main_block_desc_0* Desc;
  MJPerson *__weak weakPerson;
  __main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, MJPerson *__weak _weakPerson, int flags=0) : weakPerson(_weakPerson) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
  MJPerson *__weak weakPerson = __cself->weakPerson; // bound by copy

                __attribute__((objc_ownership(strong))) MJPerson *strongPerson =weakPerson;
                NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_47b66f_mi_0, ((int (*)(id, SEL))(void *)objc_msgSend)((id)strongPerson, sel_registerName("age")));
            }
static void __main_block_copy_0(struct __main_block_impl_0*dst, struct __main_block_impl_0*src) {_Block_object_assign((void*)&dst->weakPerson, (void*)src->weakPerson, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static void __main_block_dispose_0(struct __main_block_impl_0*src) {_Block_object_dispose((void*)src->weakPerson, 3/*BLOCK_FIELD_IS_OBJECT*/);}

static struct __main_block_desc_0 {
  size_t reserved;
  size_t Block_size;
  void (*copy)(struct __main_block_impl_0*, struct __main_block_impl_0*);
  void (*dispose)(struct __main_block_impl_0*);
} __main_block_desc_0_DATA = { 0, sizeof(struct __main_block_impl_0), __main_block_copy_0, __main_block_dispose_0};
int main(int argc, const char * argv[]) {
    /* @autoreleasepool */ { __AtAutoreleasePool __autoreleasepool; 
        MJBlock block;

        {
            MJPerson *person = ((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)objc_getClass("MJPerson"), sel_registerName("alloc")), sel_registerName("init"));
            ((void (*)(id, SEL, int))(void *)objc_msgSend)((id)person, sel_registerName("setAge:"), 10);

            __attribute__((objc_ownership(weak))) MJPerson *weakPerson = person;
            block = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA, weakPerson, 570425344));
        }

        NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_47b66f_mi_1);
    }
    return 0;
}

7.
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