Im doing some research to build an iOS and Android app using titanium appcelerator. The only requirement I have not being able to confirm is the possibility to upload a photo directly to Amazon S3 in a way that is compatible with iOS and Android devices.
Amazon S3 has provided a REST API so your can do it by creating a Titanium.Network.HTTPClient. For your upload case, you need to provide a PUT request to S3. If you want to do it in this way, you may need to include your S3 secret key in your client for signing your request.