how to read a huge array of bytes in chunks - pj_strset - ios

Question

I am working on an iOS project
I have to read a huge file in chunks of 4KB
Here is what I have so far:
NSData *fileData= [self getBytesFromInput];
pj_str_t text;
int chunkSize = 4*1024;
int fileSize = [fileData length];
while (fileSize>0){
if (fileSize<=chunkSize) {
chunkSize = fileSize;
fileSize=0;
}
else fileSize = fileSize-chunkSize;
pj_strset(&text, (char*)[fileData bytes], MIN([fileData length], chunkSize); //takes the first chunk
//BUT HOW TO TAKE THE NEXT CHUNK OF DATA?
//do something with the &text ....
}

Answer 1

i would refactor the code so you are also loading the files in chunks, but you can access the later chunks by adding an offset to your byte-pointer:
int currentOffset = 0;
while (fileSize>0) {
...
char* bytePointer = (char*)[fileData bytes];
pj_strset(&text, bytePointer+currentOffset, MIN([fileData length], chunkSize);
currentOffset += chunkSize;
}
EDIT:
This should do the same thing but reading the file chunk for chunk:
NSString *yourFilePath;
NSFileHandle *fileHandle = [NSFileHandle fileHandleForReadingAtPath:yourFilePath];
int chunksize = 4*1024;
pj_str_t text;
NSData *data;
while ((data = [fileHandle readDataOfLength:chunksize]) && [data length] > 0) {
pj_strset(&text, (char*)[data bytes], [data length]);
}