Question

i want covert content of NSData Which is actually i need as a double type
how can i convert it?

here
1ff46c56 7dd86f40 nsdata byte and i want in double

Answer 1

Assuming your data is exactly 8 bytes, you can convert it to a double using memcpy(3):

double ConvertNSDataToDouble(NSData *data)
{
    double d;
    assert([data length] == sizeof(d));
    memcpy(&d, [data bytes], sizeof(d));
    return d;
}

Note that this assumes that the data is in native endian format. If you know that the data is big- or little-endian, then you may need to endian-swap the bytes first.