Can Swift call a JSON array of custom objects?

As mentioned in the comment, you should build a database for this. I think, CoreData is perfect for this.
On the first launch, you can load all your data into database, but later you only need to reach the db.

Add CoreData to existing project

• New File (Cmd+N or File->New or right click on the folder)
• Select DataModel type, name it any (like CoreData, or your project name)
• Open AppDelegate and first import CoreData and add the following code into AppDelegate:

// MARK: - Core Data stack

    lazy var persistentContainer: NSPersistentContainer = {
        /*
         The persistent container for the application. This implementation
         creates and returns a container, having loaded the store for the
         application to it. This property is optional since there are legitimate
         error conditions that could cause the creation of the store to fail.
        */
        let container = NSPersistentContainer(name: "CoreData")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                 
                /*
                 Typical reasons for an error here include:
                 * The parent directory does not exist, cannot be created, or disallows writing.
                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
                 * The device is out of space.
                 * The store could not be migrated to the current model version.
                 Check the error message to determine what the actual problem was.
                 */
                fatalError("Unresolved error (error), (error.userInfo)")
            }
        })
        return container
    }()

    // MARK: - Core Data Saving support

    func saveContext () {
        let context = persistentContainer.viewContext
        if context.hasChanges {
            do {
                try context.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nserror = error as NSError
                fatalError("Unresolved error (nserror), (nserror.userInfo)")
            }
        }
    }

Create a new Entity

• Select your CoreData file
• Add Entity, name it like Airports
• Add attributes
  

Write functions what you need
First I would write a manager for this like

struct CoreDataManager {
    private static let appDelegate = UIApplication.shared.delegate as! AppDelegate
    private static let persistentContainer = appDelegate.persistentContainer

//... all the functions come here
}

• For saving, it’ better to user pagination

static func saveAirports(airports: [Airport], completion: ((Bool) -> Void)? = nil) {
        let airportsPerPage = 1000
        let pages = (Float(airports.count) / Float(airportsPerPage)).rounded(.up)
        var i: Float = 0
        var airportList = airports
        let backgroundContext = persistentContainer.newBackgroundContext()
        
        while i < pages {
            for airport in airportList.prefix(usersOnPage) {
                let airportRow = Users(context: backgroundContext)
                airportRow.id = airport.id
                airportRow.name = airport.name
                airportRow.city = airport.city
                airportRow.country = airport.country
                airportRow.icao = airport.icao
                airportRow.timeZoneName = airport.timeZoneName
                airportRow.code = airport.code
                backgroundContext.insert(airportRow)
            }
            if airportList.count >= airportsPerPage {
                airportList.removeFirst(airportsPerPage)
            } else {
                airportList.removeFirst(airportList.count)
            }
            i += 1
        }
        do {
            try backgroundContext.save()
            guard let completion = completion else { return }
            completion(true)
        } catch {
            print(error)
            guard let completion = completion else { return }
            completion(false)
        }
    }

• Sample search query

static func search(_ searchText: String) -> [Airport]? {
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Airports")
        let namePredicate = NSPredicate(format: "name CONTAINS[cd] %@", searchText)
        let idPredicate = NSPredicate(format: "id CONTAINS[cd] %@", searchText)
        let compoundPredicate = NSCompoundPredicate(type: .or, subpredicates: [namePredicate, idPredicate])
        request.predicate = compoundPredicate
        do {
            let result = try context.fetch(request)
            var airports = [Airport]()
            for airport in result as! [Airport] {
                airports.append(Airport(id: airport.id,
                name: airport.name, 
                city: airport.city,
                country: airport.country,
                icao: airport.icao,
                timeZoneName: airport.timeZoneName,
                code: airport.code)
            }
            return airports
        } catch {
            print(error)
            return nil
        }
    }

I hope this helps 🙂