Differences in Calendar between macOS and iOS

TidBITS Talk
1

I just encountered a weird difference between my macOS calendar (macOS 15.2) and my iOS calendar (iOS 17.2.2)

On the Mac I have set events for several birthdays that are set to repeat yearly and send a notification on the morning of the all-day event. When I sync these to the iPhone (using Finder and a USB connection) there are differences in the iOS calendar. Specifically, the event now spans two days with an alert on the day before.

Suspecting I might have done something wrong, I connected the iPhone/iPad to my Mojave (10.14.6) machine and did the same sync. In this case, the events correctly spanned one day with the alert on the morning of the event.

Finally, I did another sync between Sequoia and iOS and the two-day event returned.

macOS Sequoia ↔ iOS 17.2.2 wrong results
macOS Mojave ↔ iOS 17.2.2 correct results

A bug? Feature?

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It’s a bug … as described in a post from Apple’s Community discussions.

https://discussions.apple.com/thread/255845296

Having jumped from High Sierra to Sequoia, from a Mac Pro (5,1) to a Mac mini (16,11), I thought it was me, not “them” as I have been tweaking settings and learning new things daily. It turns out it’s them. :slight_smile:

I adopted the third-party software workaround suggested in the Apple Community discussion, SyncMate.

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Local Calendar and Contact syncing has been frelled since Ventura. I am curious to hear how SyncMate works out for you.

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My use of SyncMate is limited.

Expecting a solution to this “all day calendar events span two days” issue from Apple, I am using the free SyncMate feature where you are required to connect your iPhone/iPad via a USB cable for synchronization.

I am restricting the data exchanged to calendar information only. Additionally, I am not allowing a bidirectional flow; my Mac mini is where I adjust calendars and then send the results to my iPhone/iPad.

I wasted a few weeks of on-and-off investigations trying to comprehend this issue and got nowhere. Unlike the Apple Community commenter’s experience with SyncMate I found that Mac-to-iPhone/iPad was always successful. But iPhone/iPad to Mac resulted in all day events once again expending to two-day events.

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5

Doesn’t sound like a real solution then. Thanks.

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Update…

To fix the “all day” event problem I changed these entries to timed events that started at 00:00 and ended at 23:00. These synced correctly from the Mac to the iPhone.

Then I started trying things because I was…um…bored. On the iPhone, I changed all the 23-hour long events back in to all day events and that worked. Afterwards, syncing between the Mac and iPhone worked as desired.

That result led me to try another experiment. Instead of creating the “all day” events on the Mac I created them on the iPhone first. After syncing with the Mac, both Mac and iPhone had all day events that correctly spanned a single day.

There is a bug in syncing calendars from a Mac to iPhone using Finder and USB. Reading around the internet forums it’s clear that numerous bug reports have been filed and Apple is aware of the problem. Not sure they will get around to fixing it…

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Personally despair at calendar syncing. I see fails not just on Mac - iOS and vice versa, but shared calendars with my family and wife. Even BusyCal - Calendar on the same Mac…

I’ve kinda given up and just sorta trust Calendar events on my phone. Not good.

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