malformed_path error in Swift

You can find information on the required path format here: https://www.dropbox.com/developers/documentation/http/documentation#path-formats

I see you included a general description of how this is set up in the comments in your code, but if you need help debugging this, please share some actual code for reproducing this issue so we can investigate. Also, please print out and share the actual value of "filename" when this occurs for you.