unzip NSData using objective zip - objective-c

Question

I have just recently found Objective Zip Ihave been reading through the instructions to get it set up in my project. However I am not really sure how to use it to decompress some NSData I have that I am wanting to decompress.
I have looked at the example solution and it seems to be performing the unzip on a zip file the code looks roughly like this
ZipFile *unzipFile= [[ZipFile alloc] initWithFileName:filePath mode:ZipFileModeUnzip];
[unzipFile goToFirstFileInZip];
ZipReadStream *read1= [unzipFile readCurrentFileInZip];
give or take some other instructions this is how they show you to use it, their sample code is here
I would like to know how to do the same thing but using NSData? or would I have to convert the NSData into a zipFile? if so how is that performed properly?
The NSData I am trying to unzip if zlib compressed... any example code would be helpful

Answer 1

here it is https://stackoverflow.com/a/6466832/751885
I use the following two methods process NSData
and call
saveToFile
method write on disk.
[[self compressData:uncompressedData] writeToFile:#"fileName.zip" atomically:YES];
Compress:
-(NSData*) compressData:(NSData* )uncompressedData {
if ([uncompressedData length] == 0) return uncompressedData;
z_stream strm;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
strm.opaque = Z_NULL;
strm.total_out = 0;
strm.next_in=(Bytef *)[uncompressedData bytes];
strm.avail_in = (unsigned int)[uncompressedData length];
// Compresssion Levels:
// Z_NO_COMPRESSION
// Z_BEST_SPEED
// Z_BEST_COMPRESSION
// Z_DEFAULT_COMPRESSION
if (deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, (15+16), 8, Z_DEFAULT_STRATEGY) != Z_OK) return nil;
NSMutableData *compressed = [NSMutableData dataWithLength:16384]; // 16K chunks for expansion
do {
if (strm.total_out >= [compressed length])
[compressed increaseLengthBy: 16384];
strm.next_out = [compressed mutableBytes] + strm.total_out;
strm.avail_out = (unsigned int)([compressed length] - strm.total_out);
deflate(&strm, Z_FINISH);
} while (strm.avail_out == 0);
deflateEnd(&strm);
[compressed setLength: strm.total_out];
return [NSData dataWithData:compressed];
}
Uncompress:
-(NSData*) uncompressGZip:(NSData*) compressedData {
if ([compressedData length] == 0) return compressedData;
NSUInteger full_length = [compressedData length];
NSUInteger half_length = [compressedData length] / 2;
NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length];
BOOL done = NO;
int status;
z_stream strm;
strm.next_in = (Bytef *)[compressedData bytes];
strm.avail_in = (unsigned int)[compressedData length];
strm.total_out = 0;
strm.zalloc = Z_NULL;
strm.zfree = Z_NULL;
if (inflateInit2(&strm, (15+32)) != Z_OK) return nil;
while (!done) {
// Make sure we have enough room and reset the lengths.
if (strm.total_out >= [decompressed length]) {
[decompressed increaseLengthBy: half_length];
}
strm.next_out = [decompressed mutableBytes] + strm.total_out;
strm.avail_out = (unsigned int)([decompressed length] - strm.total_out);
// Inflate another chunk.
status = inflate (&strm, Z_SYNC_FLUSH);
if (status == Z_STREAM_END) {
done = YES;
} else if (status != Z_OK) {
break;
}
}
if (inflateEnd (&strm) != Z_OK) return nil;
// Set real length.
if (done) {
[decompressed setLength: strm.total_out];
return [NSData dataWithData: decompressed];
} else {
return nil;
}
}