UPDATE: There seem to be scenarios where “Auto Lock: never” is not available (use of Exchange mail on iOS appears to be one of them). In that case, you can’t keep your iDevice alive for longer than 5 minutes without interacting with it manually. This does not work well for long (in particular initial) DT syncs. In that case, the method outlined below of playing a long video inside DT comes in handy. Thanks to Greg_Jones for the Exchange hint.
I have not researched this carefully, so there might be some “normal” solutions that I missed. I had to get a new iPhone, and as a result I had to sync about 7 GB of DBs onto the new phone. From what I can tell, the longest iOS will stay active is 5 minutes. After that the “lock screen” mechanism kicks in and DTTG syncing stops. That made the process painful.
Playing a video keeps the phone alive indefinitely, without user interaction and playing that video inside DTTG keeps the latter indefinitely running in the foreground. I used Quicktime on the Mac to record a tiny, static 30x30 area of the screen for almost an hour, compressed it to 1.8 MB and put it in DTTG (named it “Keep DT going.mov”, disable sound track to keep file small). Start playing it and then start the sync process which happily hums away (best to keep phone plugged into charger for this). I only have to check progress within the hour (or could trivially make a longer video; there seems to be no “loop” option for playing video in DTTG, otherwise one could go indefinitely).
Is there a straightforward, official, way to force unattended, prolonged syncing?
Turning off auto lock was of course my first plan, but on my phone with the latest iOS, you can only choose a finite time between 30 secs and 5 min. I suspect that Apple forces this to avoid battery drainage.
That’s why the video trick works. Apple can be drastic, but if they prevent people from watching movies on iDevices, sales would crash.
Now that’s interesting. I have an iPhone X on 11.3.1 (which is the newest, you must be in a beta program?).
“Display & Brightness > Auto Lock” has only settings between 30 sec and 5 min, nothing else there, nothing greyed out, no other switch that could be thrown to enable further options. I also went through other menus, such as Accessibility, to see whether something could be there, but I didn’t find any smoking gun.
I also checked my iPadPro and my old iPhone 6. Under 11.3.1, they also don’t show a “never” option for Auto Lock. I plugged the phone into the charger to see whether then “never” might become available, but no (that would actually make sense, and be compatible with Apple’s strict battery lifetime attitudes).
I am quite certain that in the distant past there was such a thing on my iDevices.
Could
(1) the offered settings be region specific?
(2) there be another path in the extended Settings menus to set Auto Lock?
Bingo! Now that’s why the Forum is so useful. How would one ever find that out! Indeed, our university switched to Exchange a few years ago. I can’t get out of using that, so I’ll have to go with my video-keeps-iphone-alive method.