Add feature id to annotations; prepare showcase of callout annotations

[kiryldz]

Summary of changes

Expose unique feature identifier for all annotations created by annotation plugin. This feature id is used when preparing a Feature that backs up annotation. This feature id could now be used to connect annotation with view annotation.

Prepare an example of annotation usage (drawing a marker) and associated view annotation.

device-2021-12-15-093611.mp4

User impact (optional)

Pull request checklist:

• Briefly describe the changes in this PR.
• Include before/after visuals or gifs if this PR includes visual changes.
• Write tests for all new functionality. If tests were not written, please explain why.
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• Add example if relevant.
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Fixes: < Link to related issues that will be fixed by this pull request, if they exist >

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[macdrevx]

The iOS SDK has used the annotation id as the feature ID since v10.0.0: https://github.com/mapbox/mapbox-maps-ios/blob/v10.0.0/Sources/MapboxMaps/Annotations/Generated/PointAnnotation.swift#L25

It defaults the IDs to a UUID string, but developers can provide any string they like: https://github.com/mapbox/mapbox-maps-ios/blob/main/Sources/MapboxMaps/Annotations/Generated/PointAnnotation.swift#L45

Some alignment questions:

• Is it necessary to prefix the ID? If not, we could be aligned without any changes to iOS.
• If we choose not to prefix, could we eliminate the new featureIdentifier property and just document that id is used as the underlying feature ID?

Overall, I like the concept.

[kiryldz]

The iOS SDK has used the annotation id as the feature ID since v10.0.0: https://github.com/mapbox/mapbox-maps-ios/blob/v10.0.0/Sources/MapboxMaps/Annotations/Generated/PointAnnotation.swift#L25

It defaults the IDs to a UUID string, but developers can provide any string they like: https://github.com/mapbox/mapbox-maps-ios/blob/main/Sources/MapboxMaps/Annotations/Generated/PointAnnotation.swift#L45

Some alignment questions:

• Is it necessary to prefix the ID? If not, we could be aligned without any changes to iOS.
• If we choose not to prefix, could we eliminate the new featureIdentifier property and just document that id is used as the underlying feature ID?

Overall, I like the concept.

@macdrevx thanks for looking into it!
I was also thinking of actually using our Annotation.id exposed already but my main concern here is that we generate it not as UUID but simply as 0, 1, 2 etc. which (at least for me) looks a bit unreliable to use such an easy id when preparing a Feature (using static method Feature.fromGeometry(geometry, properties, id)).

At the same time we can't re-use Annotation.id making generating UUID more complex from our end as it is Long and not String. That's actually why current solution is used: concat unique prefix + incremental annotation id we generate.

To sum up, at least from my understanding, perhaps there's no need to even add anything on iOS then. It would be nice to prepare similar example to show users how to use point annotation with an icon with view annotation but no need to align on Annotation.featureIdentifier as it seems we're not perfectly aligned anyway (e.g. our id is Long, there's no way to allow user provide their own feature id as we don't even assign feature an id before this PR).

[macdrevx]

Sounds good to me. Could you open a ticket for iOS to add the example? cc: @endanke is that something you could do?

[endanke]

@macdrevx @kiryldz sure! I'll open a ticket and assign myself. Although I don't think I can work on it before my holidays, but I'll pick it up in January.