以下宏定义摘抄自：GUNStep
#define BLOCK_SCOPE __block
/**
* Defines a block type. Will work whether or not the compiler natively
* supports blocks.
*/
#define DEFINE_BLOCK_TYPE(name, retTy, argTys, ...) \
typedef retTy(^name)(argTys, ## __VA_ARGS__)
#define DEFINE_BLOCK_TYPE_NO_ARGS(name, retTy) \
typedef retTy(^name)()
/**
* Calls a block. Works irrespective of whether the compiler supports blocks.
*/
#define CALL_BLOCK(block, args, ...) block(args, ## __VA_ARGS__)
/**
* Calls a block without arguments.
*/
#define CALL_BLOCK_NO_ARGS(block) block()
#define DEFINE_BLOCK_TYPE_STRUCT(name, retTy, argTys, ...) \
typedef struct {\
void *isa;\
int flags;\
int reserved;\
retTy (*invoke)(void*, argTys, ## __VA_ARGS__);\
} *name
#define DEFINE_BLOCK_TYPE_NO_ARGS_STRUCT(name, retTy) \
typedef struct {\
void *isa;\
int flags;\
int reserved;\
retTy (*invoke)(void*);\
} *name
#define CALL_BLOCK_STRUCT(block, args, ...) block->invoke(block, args, ## __VA_ARGS__)
#define CALL_BLOCK_NO_ARGS_STRUCT(block) block->invoke(block)
