Gave some love to those blocks

Gave some love to those blocks, basically: 

* 781e4dc14ea51b9d5cf0998d2503fb6e675d9c0d: All the blocks use the same signature, I type-defed them to improve readability and consistency. 

* a6677b72649be2b2f5a86267e3134cb99da728a2: If you send ```nil``` to any of the block parameters, BAM!! :bomb:   An ```EXC_BAD_ACCESS``` error will happen and will cause the app to crash. Since they are public methods, I consider  wise to guard them against possible scenarios where this might happen.