How to parse json data that provides another url with more data - ios

Question

I'm a little confused how would I parse a json API that gives me 20 objects but then gives me a key of "next" having a url that gives me another 20 objects. I'm using this Pokemon API. It gives me 4 keys: count, previous, results and next. I'm trying to display them all in a collection view but not all at the same time. I would like to load more when the collection view is scrolling down.
I'm just trying to get the name at the moment. This is how my code looks like.
I get it to load the first 20 Pokemon in the collection view. However I don't know how to load the next 20 Pokemon or the 20 after. This is how the json file looks like if the link didn't work.
I would appreciate any help given. :)

Answer 1

You can try using a recursive function reusing the loadPokemonsData function something like this:
func loadPokemonsData(url: String, quantity: Int?) {
let request = URLRequest(url: URL(string: url)!)
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
if error != nil {
print(error!)
}
do {
let jsonResults = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as! NSDictionary
let pokemonArray = jsonResults.value(forKey: "results") as! [[String: Any]]
var isPokemonsEqualsToQuantity: Bool = false
for pokemonData in pokemonArray {
if let quantity = quantity {
guard self.pokemons.count < quantity else {
isPokemonsEqualsToQuantity = true
break
}
}
guard let name = pokemonData["name"] as? String else {
return
}
self.pokemon = Pokemon(name: name)
self.pokemons.append(self.pokemon)
}
guard let nextURL = jsonResults.value(forKey: "next") as? String, !isPokemonsEqualsToQuantity else {
for pokemon in self.pokemons {
print(pokemon.name)
}
print(self.pokemons.count)
return
}
self.loadPokemonsData(url: nextURL, quantity: quantity)
} catch let err as NSError {
print(err.localizedDescription)
}
}
task.resume()
}
Attach a screen of algorithm function running... it prints 791 pokemons.
Hope it helps you!
EDITED
Next time you ask put your code please... it will be easier help you!.
I've updated the code to set the quantity you want (nil if you want to get all pokemons), Therefore it will only get the pokemons in the order API returns it, if you want a specific pokemons from ALL pokemons you may do a sort after obtaining all pokemons.