Images picked from the gallery do not preserve metadata when saved to tmp. Particularly they lose GPS metadata.
This extra metadata is available in asset.defaultRepresentation.metadata.
I have a solution that works for my purpose. But currently only saving with asset.defaultRepresentation.fullResolutionImage.
Approach to get the asset: https://github.com/foundry/UIImageMetadata
Approach to save the asset: http://stackoverflow.com/a/15398387/618412 (answer from Andrew Theis).
Thanks for consideration.