How to Solve NSArray element failed to match the Swift Array Element type in GooglePlaces API findAutocompletePredictions?

Question

I am having trouble analyzing the results given by the callback of GMSPlacesClient findAutocompletePredictionsFromQuery:, which is a GMSAutocompletePrediction array.

The app will crash on let searchResultsWayPoints = finalResults.map , stating

Precondition failed: NSArray element failed to match the Swift Array Element type
Expected GMSAutocompletePrediction but found GMSAutocompletePrediction

func getGoogleWayPoint(text: String) -> Promise<[GoogleWayPoint]> {
        return Promise<[GoogleWayPoint]> { resolver in
            if text.isEmpty {
                resolver.fulfill([])
                return
            }
            placesClient.findAutocompletePredictions(fromQuery: text, filter: filter, sessionToken: sessionToken) { (results, error) in
                if let error = error {
                    dprint(error.localizedDescription)
                    resolver.fulfill([])
                    return
                }


                guard let finalResults = results else {
                    dprint("can't found results")
                    resolver.fulfill([])
                    return
                }
                let searchResultsWayPoints = finalResults.map {
                    GoogleWayPoint(id: $0.placeID, address: $0.attributedFullText.string)
                }
                resolver.fulfill(searchResultsWayPoints)
            }
        }
    }

Any help would be appreciated. Thank you.

Dupe of https://stackoverflow.com/questions/25484554/fatal-error-nsarray-element-failed-to-match-the-swift-array-element-type — ReinstateMonica3167040, Jun 24 '20 at 13:26
Actually, it is not really a dupe, as their solution doesn't work here. — Jimmy, Jun 28 '20 at 06:09

score 1 · Accepted Answer · answered Jun 10 '20 at 05:29

So I have solved this problem, but I did not fix anything, since it is from the GooglePlaces framework.

In order to solve this, simply make results as results:[Any]? at the callback.

Then, at guard let, safely convert it to [GMSAutocompletePrediction].

Here is the complete code

func getGoogleWayPoint(text: String) -> Promise<[GoogleWayPoint]> {
        return Promise<[GoogleWayPoint]> { resolver in
            if text.isEmpty {
                resolver.fulfill([])
                return
            }
            placesClient.findAutocompletePredictions(fromQuery: text, filter: filter, sessionToken: sessionToken) { (results: [Any]?, error) in
                if let error = error {
                    dprint(error.localizedDescription)
                    resolver.fulfill([])
                    return
                }


                guard let finalResults = results as? [GMSAutocompletePrediction] else {
                    dprint("can't found results")
                    resolver.fulfill([])
                    return
                }
                let searchResultsWayPoints = finalResults.map {
                    GoogleWayPoint(id: $0.placeID, address: $0.attributedFullText.string)
                }
                resolver.fulfill(searchResultsWayPoints)
            }
        }
    }

How to Solve NSArray element failed to match the Swift Array Element type in GooglePlaces API findAutocompletePredictions?

1 Answers1