How to update an array when parsing an API - ios

Question

Hello guys I taking this course online and there is a similar function that looks like this.
typealias DownloadCompleted = () -> ()
var pokemonId = 0
func fetchPokemon(url: String, completed: #escaping DownloadCompleted) {
let context = coreData.persistentContainer.viewContext
let url = URLRequest(url: URL(string: url)!)
let task = URLSession.shared.dataTask(with: url) { (data, repsonse, error) in
if error != nil {
print(error!)
}
do {
let jsonResult = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as! NSDictionary
let jsonArray = jsonResult.value(forKey: "results") as! [[String: Any]]
for pokemonData in jsonArray {
self.pokemonId += 1
if self.pokemonId > 721 {
self.coreData.saveContext()
return
}
guard let name = pokemonData["name"] as? String else {
return
}
let pokemon = Pokemon(context: context)
pokemon.name = name
pokemon.id = self.pokemonId
print("Name: \(pokemon.name) Id:\(self.pokemonId)")
}
guard let nextURL = jsonResult.value(forKey: "next") as? String else {
return
}
DispatchQueue.main.async {
self.fetchPokemon(url: nextURL, completed: {
})
}
completed()
} catch let err {
print(err.localizedDescription)
}
}
task.resume()
}
I'm trying to set an array equal to the 721 Pokemon once the function is finished parsing the data. I really don't understand how the completed() works. I want the completed to get called once it finished parsing the 721. However in my case it gets called right after the first 20 Pokemon. Can someone please help me understand how the completed() works.
Would appreciate any help, links or articles about how it works. Thanks :)

Answer 1

i am not sure if i understood your question correctly but if you want completed() block to be executed once parsing is done for 721 Pokemon.
Call completed() block in for loop when condition >= 721 Try changing your code like below
for pokemonData in jsonArray {
self.pokemonId += 1
if self.pokemonId > 721 {
self.coreData.saveContext()
completed()
return
}
guard let name = pokemonData["name"] as? String else {
return
}
let pokemon = Pokemon(context: context)
pokemon.name = name
pokemon.id = self.pokemonId
print("Name: \(pokemon.name) Id:\(self.pokemonId)")
}