整理了_block在各种情况下的源码表现，目的是帮助自己加深对_block的理解。
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.
typedef void (^MJBlock)(void);
int main(int argc, const char * argv[]) {
@autoreleasepool {
__block __weak int age = 10;
MJBlock block2 = ^{
age = 30;
NSLog(@"age is %d", age);
};
block2();
}
return 0;
}
源码
typedef void (*MJBlock)(void);
struct __block_impl {
void *isa;
int Flags;
int Reserved;
void *FuncPtr;
};
struct __Block_byref_age_0 {
void *__isa;
__Block_byref_age_0 *__forwarding;
int __flags;
int __size;
int age;
};
struct __main_block_impl_0 {
struct __block_impl impl;
struct __main_block_desc_0* Desc;
__Block_byref_age_0 *age; // by ref
__main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, __Block_byref_age_0 *_age, int flags=0) : age(_age->__forwarding) {
impl.isa = &_NSConcreteStackBlock;
impl.Flags = flags;
impl.FuncPtr = fp;
Desc = desc;
}
};
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
__Block_byref_age_0 *age = __cself->age; // bound by ref
(age->__forwarding->age) = 30;
NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_419699_mi_0, (age->__forwarding->age));
}
static void __main_block_copy_0(struct __main_block_impl_0*dst, struct __main_block_impl_0*src) {_Block_object_assign((void*)&dst->age, (void*)src->age, 8/*BLOCK_FIELD_IS_BYREF*/);}
static void __main_block_dispose_0(struct __main_block_impl_0*src) {_Block_object_dispose((void*)src->age, 8/*BLOCK_FIELD_IS_BYREF*/);}
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;
__attribute__((__blocks__(byref))) __attribute__((objc_ownership(weak))) __Block_byref_age_0 age = {(void*)0,(__Block_byref_age_0 *)&age, 0, sizeof(__Block_byref_age_0), 10};
MJBlock block2 = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA, (__Block_byref_age_0 *)&age, 570425344));
((void (*)(__block_impl *))((__block_impl *)block2)->FuncPtr)((__block_impl *)block2);
}
return 0;
}
2.
typedef void (^MJBlock)(void);
int main(int argc, const char * argv[]) {
@autoreleasepool {
__block __weak int age = 10;
MJBlock block1 = ^{
__strong int myage = age;
age = 20;
NSLog(@"age is %d", age);
};
block1();
}
return 0;
}
源码
typedef void (*MJBlock)(void);
struct __block_impl {
void *isa;
int Flags;
int Reserved;
void *FuncPtr;
};
struct __Block_byref_age_0 {
void *__isa;
__Block_byref_age_0 *__forwarding;
int __flags;
int __size;
int age;
};
struct __main_block_impl_0 {
struct __block_impl impl;
struct __main_block_desc_0* Desc;
__Block_byref_age_0 *age; // by ref
__main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, __Block_byref_age_0 *_age, int flags=0) : age(_age->__forwarding) {
impl.isa = &_NSConcreteStackBlock;
impl.Flags = flags;
impl.FuncPtr = fp;
Desc = desc;
}
};
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
__Block_byref_age_0 *age = __cself->age; // bound by ref
__attribute__((objc_ownership(strong))) int myage = (age->__forwarding->age);
(age->__forwarding->age) = 20;
NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_05aebe_mi_0, (age->__forwarding->age));
}
static void __main_block_copy_0(struct __main_block_impl_0*dst, struct __main_block_impl_0*src) {_Block_object_assign((void*)&dst->age, (void*)src->age, 8/*BLOCK_FIELD_IS_BYREF*/);}
static void __main_block_dispose_0(struct __main_block_impl_0*src) {_Block_object_dispose((void*)src->age, 8/*BLOCK_FIELD_IS_BYREF*/);}
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;
__attribute__((__blocks__(byref))) __attribute__((objc_ownership(weak))) __Block_byref_age_0 age = {(void*)0,(__Block_byref_age_0 *)&age, 0, sizeof(__Block_byref_age_0), 10};
MJBlock block1 = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA, (__Block_byref_age_0 *)&age, 570425344));
((void (*)(__block_impl *))((__block_impl *)block1)->FuncPtr)((__block_impl *)block1);
}
return 0;
}
3.
int main(int argc, const char * argv[]) {
@autoreleasepool {
__block MJPerson *person = [[MJPerson alloc] init];
MJBlock block = [^{
NSLog(@"%p", person);
} copy];
NSLog(@"%@",[block class]);
block();
}
return 0;
}
源码
typedef void (*MJBlock) (void);
struct __Block_byref_age_0 {
void *__isa;
struct __Block_byref_age_0 *__forwarding;
int __flags;
int __size;
int age;
};
struct __main_block_desc_0 {
size_t reserved;
size_t Block_size;
void (*copy)(void);
void (*dispose)(void);
};
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;
struct __Block_byref_age_0 *age;
};
struct __Block_byref_person_0 {
void *__isa;
__Block_byref_person_0 *__forwarding;
int __flags;
int __size;
void (*__Block_byref_id_object_copy)(void*, void*);
void (*__Block_byref_id_object_dispose)(void*);
MJPerson *__strong person;
};
struct __main_block_impl_0 {
struct __block_impl impl;
struct __main_block_desc_0* Desc;
__Block_byref_person_0 *person; // by ref
__main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, __Block_byref_person_0 *_person, int flags=0) : person(_person->__forwarding) {
impl.isa = &_NSConcreteStackBlock;
impl.Flags = flags;
impl.FuncPtr = fp;
Desc = desc;
}
};
static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
__Block_byref_person_0 *person = __cself->person; // bound by ref
NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_48cd6f_mi_0, (person->__forwarding->person));
}
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, 8/*BLOCK_FIELD_IS_BYREF*/);}
static void __main_block_dispose_0(struct __main_block_impl_0*src) {_Block_object_dispose((void*)src->person, 8/*BLOCK_FIELD_IS_BYREF*/);}
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;
__attribute__((__blocks__(byref))) __Block_byref_person_0 person = {(void*)0,(__Block_byref_person_0 *)&person, 33554432, sizeof(__Block_byref_person_0), __Block_byref_id_object_copy_131, __Block_byref_id_object_dispose_131, ((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)((MJPerson *(*)(id, SEL))(void *)objc_msgSend)((id)objc_getClass("MJPerson"), sel_registerName("alloc")), sel_registerName("init"))};
MJBlock block = (__strong MJBlock)((id (*)(id, SEL))(void *)objc_msgSend)((id)((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA, (__Block_byref_person_0 *)&person, 570425344)), sel_registerName("copy"));
NSLog((NSString *)&__NSConstantStringImpl__var_folders_mm_hfgvs481081__0wdsw776zfh0000gn_T_main_48cd6f_mi_1,((Class (*)(id, SEL))(void *)objc_msgSend)((id)block, sel_registerName("class")));
((void (*)(__block_impl *))((__block_impl *)block)->FuncPtr)((__block_impl *)block);
}
return 0;
}