URLSession feature flag leads to broken video uploads on self-hosted sites

[SiobhyB]

Expected behavior

Videos uploaded to self-hosted sites should function as expected.

Actual behavior

With non-production builds, videos are currently being uploaded with an invalid format to self-hosted sites. This happened following the change in #22540, which defaulted to using URLSession in WordPressKit (instead of Alamofire).

An error like the following can be seen when attempting to view iOS-uploaded videos in the media library on the web:

Media error: Format(s) not supported or source(s) not found[Download](https://example.com.mp4?_=4)

Additionally, when uploaded to the editor, the videos won't play back.

Note, this isn't an issue on dotcom or Jetpack-connected sites, only self-hosted sites with no Jetpack connection.

Steps to reproduce the behavior

• Set up a self-hosted site that doesn't have the Jetpack plugin enabled.
• Download a non-production build of the iOS, such as the installable build generated with this PR.
• Navigate to the post/page editor for your self-hosted site.
• Add the video block and choose the option to upload a video from your device.
• Observe that the block's thumbnail is blank and tapping to play results in a blank player.
• On the web, navigate to the site's media library and view the following error alongside the uploaded video: Media error: Format(s) not supported or source(s) not found[Download](https://example.com.mp4?_=4)

The feature flag that enables URLSession in WordPressKit can be toggled off via Me → App Settings → Feature Flags (note, I found it necessary to reboot the app for these changes to take effect). Toggling the flag off, however, doesn't fix the issue and leads to failed video uploads.

Tested on iPhone XR, iOS 17.3.1, Jetpack iOS / WordPress iOS non-production builds only

[dangermattic]

Thanks for reporting! 👍

[SiobhyB]

@crazytonyli, I wanted to surface this issue for you. Would you be able to take a look? With the current state, it's tricky to manually test whether changes to the video block work as expected for self-hosted sites, as all uploads are failing for non-production builds.

[crazytonyli]

@SiobhyB Thanks for reporting the issue! I have created a fix in wordpress-mobile/WordPressKit-iOS#734. I'll update the app once the PR is merged.