An adaptable functor (generic programming) using Blocks. An adaptable functor takes a function (or block) argument of any return type and number of arguments, and can be passed as an argument to other predicate/functors without modifying their return types and arguments (similar to the Adapter object-oriented programming design pattern).

block_pointers.m

/*
	An adaptable functor (generic programming) using Blocks. An adaptable functor takes a function (or block) argument of any return type and number of arguments, and can be passed as an argument to other predicate/functors without modifying their return types and arguments (similar to the Adapter object-oriented programming design pattern).
 */

int (^int_blk)(int) = ^ (int i) {
    printf("i == %d\n", i);
    return (int)i;
};

const void * (^const __strong int_blk_ptr)(const int (^const __strong)(int)) = ^ (const int(^const __strong int_blk_ptr_t)(int)) { // Initializes block pointer blk_ptr using block parameter blk_ptr_t
    printf("int_blk_ptr\n");
    return Block_copy((const void *)CFBridgingRetain(int_blk_ptr_t));
};

((__bridge const int(^const __strong)(int))(int_blk_ptr(CFBridgingRelease((__bridge CFTypeRef _Nullable)(int_blk)))))(1); // Returns a pointer to int_blk_ptr_t (prints 'int_blk_ptr' to the console) using int_blk_ptr and invokes blk (prints 'i == 1' to the console)

// Using a block literal as a parameter instead of a block variable reference
int(^re_int_blk)(int) = CFBridgingRelease((^ (const int(^const __strong int_blk_ptr_t)(int)) { // Initializes block pointer blk_ptr using block parameter blk_ptr_t
	printf("int_blk_ptr\n");
    return Block_copy((const void *)CFBridgingRetain(int_blk_ptr_t));
}(^ (int i) {
	printf("i == %d\n", i);
	return (int)i;
})));
re_int_blk(3);