BrainHack app for iPhone and iPad

BrainHack is an interpreter app for B*******k.

The B*******k programming language is an esoteric programming language noted for its extreme minimalism.
It is a Turing tarpit, designed to challenge and amuse programmers, and was not made to be suitable for practical use.
It was created in 1993 by Urban Muller.

Commands:
> increment the data pointer (to point to the next cell to the right).
< decrement the data pointer (to point to the next cell to the left).
+ increment (increase by one) the byte at the data pointer.
- decrement (decrease by one) the byte at the data pointer.
. output a character, the ASCII value of which being the byte at the data pointer.
, accept one byte of input, storing its value in the byte at the data pointer.
[ if the byte at the data pointer is zero, then instead of moving the instruction pointer forward to the next command, jump it forward to the command after the matching ] command.
] if the byte at the data pointer is nonzero, then instead of moving the instruction pointer forward to the next command, jump it back to the command after the matching [ command.