How do I read image files directly from a zip without extracting to disk?

Question

What I want to do is assign images to ui elements at runtime (think Winamp style) but I have no idea how to go about reading from a zip without storing to disk. Or how to assign each image to a ui element

I'm working on a mac with cocoa and objective c

Answer 1

Use objective-c zip (iOS/Mac zlib wrapper)

Then you can do:

ZipFile *unzipFile= [[ZipFile alloc] initWithFileName:@"test.zip" mode:ZipFileModeUnzip];
[unzipFile goToFirstFileInZip];

ZipReadStream *read= [unzipFile readCurrentFileInZip];
NSMutableData *data= [[NSMutableData alloc] initWithLength:256];
int bytesRead= [read readDataWithBuffer:data];

[read finishedReading];

Answer 2

The zipzap version:

ZZArchive* archive = [ZZArchive archiveWithContentsOfURL:[NSURL fileURLWithPath:@"test.zip"]];
NSData* data = [archive.entries[0] newDataWithError:nil];

Or if you're looking for a particular entry:

ZZArchive* archive = [ZZArchive archiveWithContentsOfURL:[NSURL fileURLWithPath:@"test.zip"]];
NSData* data = nil;
for (ZZArchiveEntry* entry in archive.entries)
  if ([entry.fileName isEqualToString:@"test.txt"])
  {
    data = [entry newDataWithError:nil];
    break;
  }

Scanning for files like this is pretty much optimal. The scan only uses the zip central directory and doesn't actually extract the data until -[entry newDataWithError:].