MFMailComposeViewController - load images inside the html

I created an MFMailComposeViewController. I attached some files using addAttachmentData:mimeType:fileName:. The files are attached successfully.

The HTML in t开发者_开发百科he message body has the following code:

<IMG border="0" style="border:0;" src="fileName.gif" >

I'm adding the attachment data with the same file name, but it isn't being loaded in the HTML. I just get a blue box with a question mark. Is there anything else I need to do in order to load the images? I'm following the documentation:

If you want to include images with your content, 
you must attach the images separately using the 
addAttachmentData:mimeType:fileName: method.
You should call this method before you display the mail composition interface 
only. Do not call it after presenting the interface to the user.