Swift中defer在oc中的实现

#ifndef nob_defer_h

#define nob_defer_h

// some helper declarations

#define _nob_macro_concat(a,b) a##b

#define nob_macro_concat(a,b) _nob_macro_concat(a,b)

typedef void(^nob_defer_block_t)();

NS_INLINE void nob_deferFunc(__strong nob_defer_block_t *blockRef)

{

nob_defer_block_t actualBlock = *blockRef;

actualBlock();

}

// the core macro

#define nob_defer(deferBlock) \

__strong nob_defer_block_t nob_macro_concat(__nob_stack_defer_block_,__LINE__) __attribute__((cleanup(nob_deferFunc),unused)) = deferBlock

#endif /* nob_defer_h */

在VC中写测试代码

- (void)viewDidLoad

{

[super viewDidLoad];

// Do any additional setup after loading the view,typically from a nib.

[self test];

- (void)test

nob_defer(^{

NSLog(@"4");

});

NSLog(@"1");

NSLog(@"2");

NSLog(@"3");

输出：

2016-09-28 15:37:44.239 testdemo[84455:5515914] 1

2016-09-28 15:37:44.239 testdemo[84455:5515914] 2

2016-09-28 15:37:48.311 testdemo[84455:5515914] 3

2016-09-28 15:37:48.311 testdemo[84455:5515914] 4