Fun way to memoize with blocks. It would be sweet if objc had decorators.

memoizer.m

#define _MEMO(iVarName, block) ^{if (!iVarName) {iVarName = (block)();} return iVarName;}

- (UIButton *)eatCheeseButton;
{
    return _MEMO(eatCheeseButton, ^{
        return [[UIButton alloc] init];
    })();
}

Not sure why it's necessary for the macro to return a block, since all you're doing with it is executing it immediately… (I could be missing something).

You could also do this without macros (if you're willing to step into C++):

template <typename T>
T memoize(T& ivar, T(^block)())
{
  if (ivar == nil) { ivar = block(); }
  return ivar;
}

- (UIButton *)eatCheeseButton
{
  return memoize(eatCheeseButton, ^{
    return [[UIButton alloc] init];
  });
}

Of course, you can do it slightly less-nicely and less safely without C++, by means of pointers to void* pointers (I hope I did this right):

void *memoize(void **ivar, void *(^block)())
{
  if (*ivar == nil) { *ivar = block(); }
  return *ivar;
}

- (UIButton *)eatCheeseButton
{
  return memoize(&eatCheeseButton, ^{
    return [[UIButton alloc] init];
  });
}