亚马逊S3通过iOS app完成上传。

I am uploading a file from an iOS app onto S3 that can get pretty large. (up to 3-5mb) I want to have a way to have a progress bar for the upload for the user to be able to see the progress of the upload. I have looked into multiple classes, but have not seen a solution. I am uploading a file from an iOS app onto S3 t