Device serial number VS uniqueIdentifier

no, that's what you get. And as far as I know the uniqueIdentifier is different for different apps on the same device.

This is how it works on most platforms I've worked with. It also changes if the app is reinstalled (I'm not sure about Garmin, but I assume it's the same) or the device is reset. That's why using such an ID is quite pointless—it's better to generate own UUID on the first launch and store it persistently, if possible.

STeN said:

It also changes if the app is reinstalled (I'm not sure about Garmin, but I assume it's the same) or the device is reset

Someone mentioned that uniqueIdentifier changes on every build, so it could be unique for a given combo of app build and device.

EDIT but it probably doesn't change on every build after all

STeN said:

That's why using such an ID is quite pointless—it's better to generate own UUID on the first launch and store it persistently, if possible.

A compromise could be to grab uniqueIdentifier on first run and persist it. Then it will persist until the app is uninstalled. (Barring any bug where app storage is unexpectedly reset on app update.)

I do agree that it's fairly pointless. EDIT: I should clarify that I mean if it really changes on every build, then there isn't too much of an advantage compared to genning your own UUID and persisting that.

Ok I was afraid that would be the case....so presumably IQ developers can generate a UUID, save it, then pass it in the .FIT file as a custom field

As far as I remember it's generated based on the device serial number + app manifest id, so if you delete the app and then install it again on the same device it'll be identical.

I don't know what's the problem. This is to easily (no user intervention) identify requests from the same app, same device. I can see why some devs would prefer if there was a way to identify a user (same user logged in on multiple devices would have the same id) but this just wasn't designed to be that. Fir that you could ask the user to type in an email address in the settings AND use a code sent to the email address (otherwise if I know your email I could do funny things) But if course there are other ways as well. One of the more commonly used way is oauth.

flocsy🤠 said:

This is to easily (no user intervention) identify requests from the same app, same device

Agreed. It does save the dev from having to generate their own UUID and persist it.

I do think it would be less useful than it could be if it really does change on rebuild, since the app would have to persist the first uniqueIdentifier it sees.

flocsy🤠 said:

As far as I remember it's generated based on the device serial number + app manifest id

That's what I thought too.

One dev recently claimed that it changes when you rebuild an app (without changing the app ID in manifest). If this is true, then it would be identical if you reinstall the app, but not if you update it.

EDIT I tried in the sim and a real device (fr955), and uniqueIdentifier doesn't seem to change on rebuild. That's a relief. In that case I'll backtrack and say that uniqueIdentifier is def more useful than genning and persisting your own UUID.

Since uniqueIdentifier was introduced, it was tied to a specific device and app app id and remains constant when apps are updated.  That in fact is it's purpose.  

I've known of apps that use it for just that for years.

Garmin didn't want to expose the device serial number for security reasons, and this is a way of "hiding" it but allowing a specific ID being tied to a specific device/app

Yes, that's what I always understood, I was just thrown off by a dev who recently claimed that it changes on every build.

Perhaps they also changed their app id in manifest, idk

No, use Unique identifier which stays constant for an app across uninstall / install on same device. Thus you can still tie subscriptions or whatever else you are doing to a device.

FlowState said:

Someone mentioned that uniqueIdentifier changes on every build, so it could be unique for a given combo of app build and device.

It doesn’t change on every build.

If it changed due to such an arbitrary event, it would be useless.

It’s specific to an app and the particular device.

FlowState said:

I do think it would be less useful than it could be if it really does change on rebuild, since the app would have to persist the first uniqueIdentifier it sees.

It does not change on rebuild. 

Stop repeating this misinformation. 

FlowState said:

Yes, that's what I always understood, I was just thrown off by a dev who recently claimed that it changes on every build.

Don’t get thrown off by what random “developers “ claim. You probably have much more experience than they do.

It would be useless to have it change so arbitrarily.