Split NSData objects into other NSData objects of a given size

Question

I have an NSData object of approximately 1000kB in size. Now I want to transfer this via Bluetooth. It would be better if I have, let\'s say, 10 objects of 100kB. It comes t

Answer 1

The following piece of code does the fragmentation without copying the data:

NSData* myBlob;
NSUInteger length = [myBlob length];
NSUInteger chunkSize = 100 * 1024;
NSUInteger offset = 0;
do {
    NSUInteger thisChunkSize = length - offset > chunkSize ? chunkSize : length - offset;
    NSData* chunk = [NSData dataWithBytesNoCopy:(char *)[myBlob bytes] + offset
                                         length:thisChunkSize
                                   freeWhenDone:NO];
    offset += thisChunkSize;
    // do something with chunk
} while (offset < length);

Sidenote: I should add that the chunk objects cannot safely be used after myBlob has been released (or otherwise modified). chunk fragments point into memory owned by myBlob, so don't retain them unless you retain myBlob.