Blocks自测

Test 1

Example A
void exampleA() {
  char a = 'A';
  ^{
    printf("%c\n", a);
  }();
}
1、always works ?
2、only works with ARC ?
3、only works without ARC ?
4、never works ?

Example B
void exampleB_addBlockToArray(NSMutableArray *array) {
  char b = 'B';
  [array addObject:^{
    printf("%c\n", b);
  }];
}
void exampleB() {
  NSMutableArray *array = [NSMutableArray array];
  exampleB_addBlockToArray(array);
  void (^block)() = [array objectAtIndex:0];
  block();
}
1、always works ?
2、only works with ARC ?
3、only works without ARC ?
4、never works ?

Example C
void exampleC_addBlockToArray(NSMutableArray *array) {
  [array addObject:^{
    printf("C\n");
  }];
}
void exampleC() {
  NSMutableArray *array = [NSMutableArray array];
  exampleC_addBlockToArray(array);
  void (^block)() = [array objectAtIndex:0];
  block();
}
1、always works ?
2、only works with ARC ?
3、only works without ARC ?
4、never works ?

Example D
typedef void (^dBlock)();
dBlock exampleD_getBlock() {
  char d = 'D';
  return ^{
    printf("%c\n", d);
  };
}
void exampleD() {
  exampleD_getBlock()();
}
1、always works ?
2、only works with ARC ?
3、only works without ARC ?
4、never works ?

Example E
typedef void (^eBlock)();
eBlock exampleE_getBlock() {
  char e = 'E';
  void (^block)() = ^{
    printf("%c\n", e);
  };
  return block;
}
void exampleE() {
  eBlock block = exampleE_getBlock();
  block();
}
1、always works ?
2、only works with ARC ?
3、only works without ARC ?
4、never works ?

题目来自parse的博文 http://blog.parse.com