When a form entry is completed, the answer values are prioritised and uploaded first.
The size of the answers are also generally quite small and thus upload fast, even on slow network connections.
However media files such as photos, audio and video are each much larger in size and thus take longer to upload.
Video files are generally the largest files (and thus take the longest to upload), with audio and photos usually being smaller but still significant in size – e.g. in the region of 500 kilobytes.
Mobile devices also do not allow apps to run for long in the background before either killing or sleeping the apps.
This is because power conservation is a key aspect of a mobile operating system – the less apps running, the less battery life consumed.
So generally when the app is in the background or closed, your media file uploads may not have sufficient time to complete before the app is stopped.
In this case, the files will remain on the device waiting for the next time the app is opened before these can continue uploading.
Additionally if the app is forcibly closed by the user – e.g. by swiping the app off of the “open apps” view in iOS or Android – then the mobile operating system will kill the app, which in turn stops any background uploads the app was running.
What app users can do to ensure uploads are completed
When finished using the app, your users should not kill it – rather they should simply push the app to the background.
This is easily done by either switching to another app or by hitting the home button on the device.
Users should not swipe the app off the “open apps” view of their device, rather just they should leave it in the apps list even when not in use.
If uploads are slow or not successfully uploaded, mobile users can help by keeping the app open and “awake” in the foreground, or by re-opening the app when they are next on a faster network connection (e.g. an office Wi-fi connection).
This should assist the app with having more time to upload outstanding files.