+ (BOOL)unzipFileAtPath:(NSString *)path toDestination:(NSString *)destination progressHandler:(void (^)(NSString *entry, unz_file_info zipInfo, long entryNumber, long total))progressHandler completionHandler:(void (^)(NSString *path, BOOL succeeded, NSError *error))completionHandler

- (void)downloadManager:(id)sender finishedDownload:(ANDownload *)download {
    if ( [[NSFileManager defaultManager] fileExistsAtPath:download.storeFile] ) {
      NSLog(@"Download exists");
      [self.labelStep setText:CustomLocalizedString(@"ZIP_DECOMPRESSING_MSG", nil)];

      [SSZipArchive unzipFileAtPath:download.storeFile toDestination:self.saveFolderPath progressHandler:^(NSString *entry, unz_file_info zipInfo, long entryNumber, long total) {
          //Your main thread code goes in here
          NSString * labelProgressText = [NSString stringWithFormat:@"%ld / %ld", entryNumber, total];
          self.labelProgress.text = labelProgressText;
       } completionHandler:^(NSString *path, BOOL succeeded, NSError *error) {
         NSLog(@"Succeeded %d in path: %@", succeeded, path);
         if(succeeded){
         .....

dispatch_async(dispatch_get_main_queue(), ^{
    //Your main thread code goes in here
    yourLabel.text = @"new text";
});

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    dispatch_async(dispatch_get_main_queue(), ^{
        //Your main thread code goes in here
        yourLabel.text = @"new text";
    });
}