Castro and Overcast both allow sideloading to your Phone but neither seems to support transferring those sideloaded files to the Watch. Syncing seems to be spotty regardless of the app. So, I've been watching this thread, hoping someone has discovered an app that will do this well, while continuing the hunt on my own.
And: success. Read on. (The following includes many updates over several days.)
Executive Summary
iCatcher is an excellent, stable, low-cost and highly functional app for playing non-DRM audio and audiobook files independently and off-network on the Watch, as well as normal podcasts.
How to side load audio files into iCatcher
Method 1:
Use iCatcher's built-in tool from within the Imported Media "podcast" (or any other) to transfer files from iCloud or other Files.app-compatible cloud service:
The steps:
- Start with the iCatcher app on your iPhone. In the Settings pane in the iPhone app, select Import Media.
- Click Import From... and navigate to your .MP3 audio files. Your files can be in Dropbox, in iCloud, or wherever else might be convenient. UPDATE: iCloud seems more reliable. Best to first open the Files app to ensure that the files you want to import are actually resident on your phone-- if you see a cloud icon for a file in the Files app, click it so it downloads. (Commence the file imports from within iCatcher. I was unable to get the share menu in Dropbox's app or the Files app to convey more than one file at a time to iCatcher. This seems to be an iOS bug.)
- Click the Select button. Click on files you want to transfer. Click Open. I have had good luck selecting up to 30-40 files at a time on my iPhone XS. Above 40-some files, the select process can hang. This may be a RAM thing and if so, the maximum number of files you can work with at a time might be different for a different phone model. Again, iCloud has seemed more reliable. If you have piles of files, you can always import in batches. The process is fast.
- The files will appear under the "Available for Import" label. Click the All button at the upper right corner. Click the Next button.
- Under the "Podcast & Episode Selection" you can either leave this blank (in which case the file will eventually end up in a "Podcast" entitled "Imported Media") or you can enter a name for a new "Podcast" that will contain this and other files. So, this might be a good place to put the audiobook's name.
- Finally, click "Save". Now, navigate to the podcasts list.
- You'll find the newly imported files in the "podcast" you specified in step 5. In it, swipe right on each file. Click Send to Watch. There will be a small "transferring" label as it sluices across to the Watch. It's a slow process... be patient. Maybe putting it on the charger might speed things up. Unfortunately this step must be performed one at a time for your files. Transferred files seem to take time to show up in iCatcher on the Watch even after the transfer is shown as complete on the iPhone.
Method 2:
Use AirDrop to load your files from a Mac or iDevice to iCatcher on your iPhone, after which you can instruct it to transfer some or all of them to your Watch.
See post 19 in this thread.
Syncing to the Watch
iCatcher's watch sync works reliably, but you must currently specify the files to transfer manually.
In particular, iCatcher is unable to automagically transfer new files (such as automatically-downloaded daily podcasts) to the Watch. (Soon.)
Really, the
only negative regarding iCatcher is that the user interfaces for iCatcher's iPhone and Watch apps are not as slick as Castro's or Overcast's. (But it doesn't suffer the usability and discoverability fails of Castro in particular.) It's serviceable if not stylish. I'll take functionality over fashion any day.
And iCatcher is really superb in what it does, and it does all this without an upcharge or annual fee.
Independent of whatever app you choose, organizing your imported files might take some thought. In my case, I had several dozen files intended to be played in order, but the content creators' file naming system wasn't well designed for ordering the files. So, I renamed the files manually in the iCloud folder on my Mac before importing into iCatcher, adding a couple of characters at the beginning of the filename ("1a", "1b",...) to ensure a simple alphabetic listing would give me what I wanted. Then, after importing, open iCatcher on the Watch and navigate to the "podcast" containing your imported files. Force-press on the file list on the watch, and select "Pod.Title A-Z" as the ordering. (You can also do this in the Settings for iCatcher on the Watch.) The results will have podcast episodes grouped together, by title. So, your imported media will show up together and in the order you want. Frankly, I'd rather see a folder structure like other podcast apps have, and I'd love to see the ability to import a folder of files rather than dealing with them one by one. All things in time.
Summarizing: I've spent significant time (and, in the cases of Castro and Overcast, money) evaluating:
- Castro, which is gorgeous but mostly undocumented, and (for my podcast-intensive usage) unintuitive and opaque (what's the difference between the queue and inbox?). It doesn't sync to the Watch reliably and it doesn't sync sideloaded files to the Watch at all. Sideloading is part of a paid annual option, requires iCloud, and is slickly implemented.
- Overcast, also quite nicely designed... but it doesn't sync to the Watch reliably and it doesn't sync sideloaded files to the Watch at all. Sideloading is part of a paid annual option and is based on uploading your files to Overcast's server, so it can be used for files from a PC or something.
- iCatcher, which ticks all the functionality boxes. It syncs reliably to the Watch. It syncs sideloaded files to the Watch. Files can be sideloaded from any cloud service that works with your iPhone's Files app, though iCloud has so far proven to be the more trouble-free option for me so far. Files can also be sideloaded using AirDrop! See post 19 below.
Summary
iCatcher comes closest to the ideal functionality for a podcast app, especially for those like OP who want to listen to audiobooks and other files and that aren't podcasted. Suggestions for improvement might include:
- A proper folder structure on the Watch (as in its iPhone app),
- Automatic syncing to the watch when specified podcasts are updated (Edit: coming!),
- Clearer navigation on the Watch,
- Faster, less opaque transfers to the Watch (are you listening, Apple?)
As a bonus, the developer is responsive and eager for feedback. He doesn't charge for all this functionality, and there are no annual in-app purchases or subscription fees. The app does have a tip-jar, and I highly recommend you use it, as this app is a keeper.