SyncDelegate availability on non-Wi-Fi devices

While adding Wi-Fi support to my app, I ran into a small but confusing quirk.

Some devices that don’t have Wi-Fi still expose the SyncDelegate class, for example the fenix 7X Pro Solar Edition or the Forerunner 165. Others don’t expose it at all, like the Forerunner 255 or the Edge MTB. This is actually documented correctly in the API spec:
https://developer.garmin.com/connect-iq/api-docs/Toybox/Communications/SyncDelegate.html

In my case this caused a crash, because I had a method inside SyncDelegate that other parts of the app used to check whether a sync was currently running. On devices where SyncDelegate isn’t available, that obviously doesn’t end well.

Once I understood what was going on, the fix was easy enough: just check whether SyncDelegate is available before using it.

What I’m still wondering about is why this class exists on some non-Wi-Fi devices but not on others. From the outside it feels a bit arbitrary. Am I missing some architectural detail here?

Curious to hear your thoughts.

jim_m_58 3 days ago

Try using "has" for things that will only function if the device has wifi.

the-ninth 2 days ago in reply to jim_m_58

Yes, as I mentioned, I know how to fix it. I am simply trying to understand whether there is any logical reason why some non-Wi-Fi devices have the class and others do not.

flocsy🤠 2 days ago

why do you think that it is only possible to sync via wifi?

the-ninth 2 days ago in reply to flocsy🤠

flocsy🤠 said:
why do you think that it is only possible to sync via wifi?

You are right, sync also works over a Bluetooth connection. So I can see the advantage of supporting this on non-Wi-Fi devices as well, mainly for compatibility reasons, so that an app implementing sync can run without modifications.

However, that still does not explain why some devices do not support sync at all.

jim_m_58 2 days ago in reply to the-ninth

It can depend on a number of things, like age of device, api-level, and even memory on the device. Remember, you are looking at devices that were released over the last decade or so,

flocsy🤠 2 days ago

I don't understand then what is the issue. According to the documentation SyncDelegate is there on fr165. And according to the docs the whole class with all the 3 methods should be there. If this is not the case then open a bug report with the relevant exception from ERA.

the-ninth 2 days ago in reply to flocsy🤠

flocsy🤠 said:
I don't understand then what is the issue. According to the documentation SyncDelegate is there on fr165. And according to the docs the whole class with all the 3 methods should be there. If this is not the case then open a bug report with the relevant exception from ERA.

No issue at all. I was simply curious about the reasoning behind it. If sync via Bluetooth makes sense in principle, I am wondering why devices like the FR255 and the Edge MTB do not support it.

flocsy🤠 2 days ago in reply to the-ninth

Then what caused the crash?

the-ninth 2 days ago in reply to flocsy🤠

The crash occurred because I was not aware that the Edge MTB does not implement the SyncDelegate class. Once I understood that, it was easy to fix in my case. However, it could require more effort to adapt an app that relies exclusively on sync mode for certain types of communication.

Avoiding that kind of special handling for non-Wi-Fi devices is, I assume, the main reason it would make sense to provide sync support on those devices as well.

That is why it feels somewhat arbitrary that some of them do not support it.