[iOS 13] Font size increases when edited on multiple platforms

Symptoms

Under certain uncommon conditions, text that has been edited by a mobile device and copied back to a Mac (and potentially a PC, though we do not have any confirmation of that happening) will have its base font size increased by a certain percentage. E.g. 12pt Times New Roman will be set to 15.6 Times New Roman. This cycle will continue indefinitely if it is not corrected.

Cause

Apple has come to the conclusion, with iOS 13, that the best way to handle the perceptual differences between mobile and full size screens is to, instead of scaling the font dynamically to a more comfortable size, actually change the font size itself in word processing documents. This makes their ecosystem, in its default configuration, uniquely unsuitable to any form of design or scenarios where specifications (like having 12pt fonts in your document) are required. It also makes unmodified editors potentially unable to work with other operating systems (even their own), unless all operating systems and text editors in the world modify how they work to read Apple's proprietary and off-specification codes, to treat what would normally be done with zooming, as a font size adjustment.

They have at least had the foresight to provide an option to turn this off, which doesn't do anything for any text editors that already exist---but at least going forward we can put a stop to this practice. Scrivener 1.2 will have the necessary code to opt out of this behaviour, and ensure that when you say you want an 18pt heading, you really will get an 18pt heading and not something that has been upscaled to "look" like 18pts does on an Mac, when viewed on your iPad.

Workaround

Firstly: check the App Store for Scrivener 1.2, and update your copy. This should fix the problem permanently. At the time of this writing, 1.2 is available for upgrade. We strongly recommend you apply it as soon as you upgrade to iOS 13.

If for any reason you cannot update, the following procedure will help you keep your font sizes correct. You will need to fix the font sizes of your text when returning to the Mac. Given how this can occur in any file that has been modified, it will be best to make use of a feature that will alert you of every such file:

  1. In the Sharing: Sync preference pane, enable both of the first options that pertain to a "Synced Documents" collection. You want this collection to be created, and to be shown to you after the project syncs in the changes from mobile.
  2. Next, after syncing, using this list as a way to select all modified documents, use the Documents ▸ Convert ▸ Text to Default Formatting menu command.

Since this command is necessarily destructive, you should always have a backup available, in case you have custom formatting that gets lost. Enabling the snapshot on sync feature can be that safety net, but also be aware that by default all projects are fully backed up prior to syncing mobile changes. This setting can be confirmed in the Backup preference pane, where you will also find a button to load the backup folder. Should you need to restore, refer to §5.2.4, Restoring from Backups in the user manual PDF, pg. 68, for further details.