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swiftmapboxmapbox-ios

Filter a Layer By a Value Contained in a Stringified JSON Array Property

One of the tables in one of our Mapbox tilesets has a stringified JSON array property of ids:

"string_ids":"[\"a\",\"b\"]"

I would like to filter features using this property, but can't seem to find a way to do it in the Predicates and Expressions documentation. So, for instance, I'd like to filter features so only those that have a "string_id" of "a" display.

I believe this will help with my problem, when ready (https://github.com/mapbox/mapbox-gl-js/issues/4113), but just wondering if there's another solution in place at this time?

UPDATE

I've tried several different approaches:

  • NSPredicate(format: "'a' IN CAST(string_ids, 'NSArray<NSString>')") errors out with: "Casting expression to NSArray not yet implemented."
  • NSPredicate(format: "string_ids contains[c] %@", "a") does not error out, but no features match the filter.
  • NSPredicate(format: "string_ids LIKE 'a'")errors out with: "NSPredicateOperatorType:7 is not supported."
Solution

  • As of v5.8.0-alpha.1 of the Mapbox iOS SDK, this is now supported.

    So, to close the loop on my original question, this predicate is now working as desired: NSPredicate(format: "string_ids contains 'a'").