在iOS或Node.js中上传到S3

I am working on an iOS app that will upload images and videos and save them per user. I was able to integrate amazon s3 and do the upload from the iOS app, I already have a node.js backend that I persist meta about the file that I saved in S3 and the S3 Id I get back from iOS. My question is : is this a good architecture, or should I move the S3 saving activity to the backend? how do other apps do it ( like instagram / vine ) should the mobile device handle that or the backend?I am working on an iOS app that will upload ima