NSURLThumbnailDictionaryKey test

preview-from-url.m

#import <Cocoa/Cocoa.h>

/*
clang -fobjc-arc -Wall preview-from-url.m -o /tmp/preview-from-url -framework Cocoa

When run on a file in my iCloud Drive:

2015-01-08 16:39:54.008 preview-from-url[23221:261259] NSURLThumbnailDictionaryKey = {
    NSThumbnail1024x1024SizeKey = "<NSImage 0x7fd6b34228f0 Size={790, 1024} Reps=(\n    \"<NSCGImageSnapshotRep:0x7fd6b34249e0 cgImage=<CGImage 0x7fd6b3423de0>>\"\n)>";
}

Copy that same file out to my Desktop:

2015-01-08 16:40:19.021 preview-from-url[23235:261769] NSURLThumbnailDictionaryKey = (null)

*/

int main(int argc, char *argv[])
{
  if (argc != 2) {
      fprintf(stderr, "usage: %s path", argv[0]);
      return 1;
  }
  
  NSString *path = [[NSFileManager defaultManager] stringWithFileSystemRepresentation:argv[1] length:strlen(argv[1])];
  NSURL *fileURL = [NSURL fileURLWithPath:path];
  
  NSFileCoordinator *coordinator = [[NSFileCoordinator alloc] initWithFilePresenter:nil];
  __autoreleasing NSError *error;
  __block BOOL success = NO;
  
  [coordinator coordinateReadingItemAtURL:fileURL options:0 error:&error byAccessor:^(NSURL *newURL){
    __autoreleasing id value;
    __autoreleasing NSError *resourceError;
    
    if (![newURL getResourceValue:&value forKey:NSURLThumbnailDictionaryKey error:&resourceError]) {
      NSLog(@"Error getting resource value: %@", resourceError);
      return;
    }
    
    NSLog(@"NSURLThumbnailDictionaryKey = %@", value);
    success = YES;
  }];
  
  if (!success) {
    NSLog(@"Failed to read file: %@", error);
    return 1;
  }
  
  return 0;
}