Returns a pointer to the data storage of the receiver.
Modifications to the memory pointed to by this pointer will
change the contents of the object. It is important that
your code should not try to modify the memory beyond the
number of bytes given by the -length
method.
NB. if the object is released, or any method that changes its size or content is called, then the pointer previously returned by this method may cease to be valid.
This is a 'primitive' method ... you need to implement it if you write a subclass of NSMutableData.
Replaces the bytes of data in the specified range with a
copy of the new bytes supplied.
If the location of the range specified lies beyond the end
of the data ([self length] < range.location
)
then a range exception is raised.
Otherwise, if the range specified extends beyond the end
of the data, then the size of the data is increased to
accomodate the new bytes.
Sets the length of the NSMutableData object. If the length is increased, the newly allocated data area is filled with zero bytes.
This is a 'primitive' method ... you need to implement it if you write a subclass of NSMutableData.