Store/retrieve in/from variable number of binary values in a hexadecimal string with Objective-C? -

i want take hexadecimal string , nsarray of bit columns (@[@(1), @(3), @(156)]) not 0 in binary value of string.

similarly, want take nsarray of bit columns indices @[@(23), @(52), @(53), @(129)] , generate hexadecimal string those.

is there reasonably efficient way of doing this?