Chunk upload of expanding file on iOS

[Cross-linking for reference: https://stackoverflow.com/questions/31328498/ios-dropbox-sdk-chunked-upload-of-open-file ]

If I understand the scenario correctly, this should work. The chunked uploading contract doesn't need (and in a way, can't) know about the state of the local file/data. It just receives the chunks of data as you send them up. As long as you send up all of the data for the eventual file, in order, specifying the correct offset, the resulting file should be what you expect.

The documentation for /chunked_upload breaks down the flow:

https://www.dropbox.com/developers/core/docs#chunked-upload

Are you sure you're uploading the pieces of the file in the right order? Also, this would only work if the format for the file you're using is such that the data in the file never changes once it's initially written. (E.g., if some important metadata is written at the beginning of the file once the recording is complete, that finalized part won't have been uploaded to Dropbox since you already uploaded the non-final version.)

It may be the last point you made.

The whole file is getting uploaded. It may be that the AVFoundation framework modifies the file header once the video recording is complete.