title: ALAsset NSURL *assetURL returns NULL
body: <p>I'm having a weird issue trying to save an image to my SavedPhotosAlbum using the ALAssetsLibrary, particularly when I'm using the writeImageToSavedPhotosAlbum method.</p>
  
  <p>Basically my issue is that the NSURL is returning null within my completion block... there is no Error, but the URL is null.</p>
  
  <p>Here's the method :</p>
  
  <pre><code>UIImage *imageToSave = [libraryPicture imageFromCurrentlyProcessedOutput];
  
  
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
    [library writeImageToSavedPhotosAlbum:[imageToSave CGImage] orientation:ALAssetOrientationUp  completionBlock:^(NSURL *assetURL, NSError *error) {
  
    NSLog(@"AssetURL: %@", assetURL);
  
    if(!error) {
      NSLog(@"\t ! Error");
      NSLog(@"\t Error: %@", [error localizedDescription]);
      NSLog(@"\t Error code %d", [error code]);
    }
  
    if(error != nil) {
      NSLog(@"\t ERROR != NIL");
      NSLog(@"\t Error - Image Failed To Save With Error: %@", [error localizedDescription]);
      NSLog(@"\t Error code %d", [error code]);
    }
  
    if(error == nil) {
      NSLog(@"\t ERROR == NIL");
    }
  
    }];
  </code></pre>
  
  <p>I use a pretty similar method just a few lines away (in another switch case) that works, and it prints the URL within an almost identical completion block (though the called method differs): </p>
  
  <pre><code>[stillCamera capturePhotoAsJPEGProcessedUpToFilter:selectedFilter withCompletionHandler:^(NSData *processedJPEG, NSError *error) {
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
    [library writeImageDataToSavedPhotosAlbum:processedJPEG metadata:stillCamera.currentCaptureMetadata completionBlock:^(NSURL *assetURL, NSError *error2) {
      if (error2 != nil) {
        NSLog(@"ERROR: the image failed to be written");
      }
      else {
        NSLog(@"PHOTO SAVED FROM STILL CAMERA - assetURL: %@", assetURL);
      }
  
    }];
  }];
  </code></pre>