gistfile1.m

- (IBAction)selectDataset:(id)sender {
    NSLog(@"Presenting picker");
    NSArray *files = [self presentPicker];
    NSLog(@"User picked %lu files.", files.count);
    self.progressBar.maxValue = files.count;
    
    // For every .dcm file, create a thread and convert it to a PVRTC texture
    dispatch_queue_t queue = dispatch_queue_create("org.denter.DICOM2PVR", NULL);
    for (NSString *fn in files) {
        dispatch_async(queue, ^{
            // Create separate process to convert the specific file. PVRTexLib
            // is not thread-safe.
            NSString *executable = [[NSBundle mainBundle] pathForAuxiliaryExecutable:@"compress"];
            assert(executable != nil);
            NSString *dest = [NSString stringWithFormat:@"%@.pvr", fn];
            NSArray *args = [NSArray arrayWithObjects:fn, dest, nil];
            NSTask *task = [NSTask launchedTaskWithLaunchPath:executable arguments:args];
            //            [task launch];
            [task waitUntilExit];
// This instead of waitUntilExit doesn't work either
//            while ([task isRunning]) {
//                ;
//            }
            // Inform main thread that we're done
            dispatch_sync(dispatch_get_main_queue(), ^{
                [self.progressBar incrementBy:1.];
            });
        });
    }
}