Array that's supposed to store JSON is empty after successful JSON parsing












1















 var pokemons = [Pokemon]()

func loadJSON() {
let url = "https://pokeapi.co/api/v2/pokemon/"
guard let urlObj = URL(string: url) else { return }

URLSession.shared.dataTask(with: urlObj) {(data, response, error) in
guard let data = data else { return }

do {
let pokedex = try JSONDecoder().decode(Pokedex.self, from: data)

for pokemon in pokedex.results {
guard let jsonURL = pokemon.url else { return }
guard let newURL = URL(string: jsonURL) else { return }

URLSession.shared.dataTask(with: newURL) {(data, response, error) in
guard let data = data else { return }

do {
let load = try JSONDecoder().decode(Pokemon.self, from: data)
self.pokemons.append(load)

} catch let jsonErr {
print("Error serializing inner JSON:", jsonErr)
}
}.resume()
}
} catch let jsonErr{
print("Error serializing JSON: ", jsonErr)
}
}.resume()
}


This code compiles and runs fine, but the array pokemons returns a count of 0 when I check its size afterwards. It's strange because if I loop through the array right after the pokemons.append(load), it'll spit out a bunch of data. It's as if the data gets lost as soon as it's out of scope of the JSON. Does my array need to be passed by reference or something? I'm looking to take the data and put it into a UITableView, but so far nothing is showing.



override func viewDidLoad() {
super.viewDidLoad()

navigationItem.title = "Pokemon"
navigationController?.navigationBar.prefersLargeTitles = true
loadJSON()
print(pokemons.count) //Prints 0
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}

override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let label = UILabel()
label.text = "By Id"
label.backgroundColor = UIColor.lightGray
return label
}

override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return pokemons.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

let name = pokemons[indexPath.row].name

cell.textLabel?.text = "(name) Section:(indexPath.section) Row:(indexPath.row)"
return cell
}









share|improve this question


















  • 1





    loadJSON is asynchronous.

    – rmaddy
    Nov 25 '18 at 16:30











  • hey! sorry I'm not familiar with what that means. Could you explain more?

    – teachMeSenpai
    Nov 25 '18 at 16:35
















1















 var pokemons = [Pokemon]()

func loadJSON() {
let url = "https://pokeapi.co/api/v2/pokemon/"
guard let urlObj = URL(string: url) else { return }

URLSession.shared.dataTask(with: urlObj) {(data, response, error) in
guard let data = data else { return }

do {
let pokedex = try JSONDecoder().decode(Pokedex.self, from: data)

for pokemon in pokedex.results {
guard let jsonURL = pokemon.url else { return }
guard let newURL = URL(string: jsonURL) else { return }

URLSession.shared.dataTask(with: newURL) {(data, response, error) in
guard let data = data else { return }

do {
let load = try JSONDecoder().decode(Pokemon.self, from: data)
self.pokemons.append(load)

} catch let jsonErr {
print("Error serializing inner JSON:", jsonErr)
}
}.resume()
}
} catch let jsonErr{
print("Error serializing JSON: ", jsonErr)
}
}.resume()
}


This code compiles and runs fine, but the array pokemons returns a count of 0 when I check its size afterwards. It's strange because if I loop through the array right after the pokemons.append(load), it'll spit out a bunch of data. It's as if the data gets lost as soon as it's out of scope of the JSON. Does my array need to be passed by reference or something? I'm looking to take the data and put it into a UITableView, but so far nothing is showing.



override func viewDidLoad() {
super.viewDidLoad()

navigationItem.title = "Pokemon"
navigationController?.navigationBar.prefersLargeTitles = true
loadJSON()
print(pokemons.count) //Prints 0
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}

override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let label = UILabel()
label.text = "By Id"
label.backgroundColor = UIColor.lightGray
return label
}

override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return pokemons.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

let name = pokemons[indexPath.row].name

cell.textLabel?.text = "(name) Section:(indexPath.section) Row:(indexPath.row)"
return cell
}









share|improve this question


















  • 1





    loadJSON is asynchronous.

    – rmaddy
    Nov 25 '18 at 16:30











  • hey! sorry I'm not familiar with what that means. Could you explain more?

    – teachMeSenpai
    Nov 25 '18 at 16:35














1












1








1








 var pokemons = [Pokemon]()

func loadJSON() {
let url = "https://pokeapi.co/api/v2/pokemon/"
guard let urlObj = URL(string: url) else { return }

URLSession.shared.dataTask(with: urlObj) {(data, response, error) in
guard let data = data else { return }

do {
let pokedex = try JSONDecoder().decode(Pokedex.self, from: data)

for pokemon in pokedex.results {
guard let jsonURL = pokemon.url else { return }
guard let newURL = URL(string: jsonURL) else { return }

URLSession.shared.dataTask(with: newURL) {(data, response, error) in
guard let data = data else { return }

do {
let load = try JSONDecoder().decode(Pokemon.self, from: data)
self.pokemons.append(load)

} catch let jsonErr {
print("Error serializing inner JSON:", jsonErr)
}
}.resume()
}
} catch let jsonErr{
print("Error serializing JSON: ", jsonErr)
}
}.resume()
}


This code compiles and runs fine, but the array pokemons returns a count of 0 when I check its size afterwards. It's strange because if I loop through the array right after the pokemons.append(load), it'll spit out a bunch of data. It's as if the data gets lost as soon as it's out of scope of the JSON. Does my array need to be passed by reference or something? I'm looking to take the data and put it into a UITableView, but so far nothing is showing.



override func viewDidLoad() {
super.viewDidLoad()

navigationItem.title = "Pokemon"
navigationController?.navigationBar.prefersLargeTitles = true
loadJSON()
print(pokemons.count) //Prints 0
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}

override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let label = UILabel()
label.text = "By Id"
label.backgroundColor = UIColor.lightGray
return label
}

override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return pokemons.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

let name = pokemons[indexPath.row].name

cell.textLabel?.text = "(name) Section:(indexPath.section) Row:(indexPath.row)"
return cell
}









share|improve this question














 var pokemons = [Pokemon]()

func loadJSON() {
let url = "https://pokeapi.co/api/v2/pokemon/"
guard let urlObj = URL(string: url) else { return }

URLSession.shared.dataTask(with: urlObj) {(data, response, error) in
guard let data = data else { return }

do {
let pokedex = try JSONDecoder().decode(Pokedex.self, from: data)

for pokemon in pokedex.results {
guard let jsonURL = pokemon.url else { return }
guard let newURL = URL(string: jsonURL) else { return }

URLSession.shared.dataTask(with: newURL) {(data, response, error) in
guard let data = data else { return }

do {
let load = try JSONDecoder().decode(Pokemon.self, from: data)
self.pokemons.append(load)

} catch let jsonErr {
print("Error serializing inner JSON:", jsonErr)
}
}.resume()
}
} catch let jsonErr{
print("Error serializing JSON: ", jsonErr)
}
}.resume()
}


This code compiles and runs fine, but the array pokemons returns a count of 0 when I check its size afterwards. It's strange because if I loop through the array right after the pokemons.append(load), it'll spit out a bunch of data. It's as if the data gets lost as soon as it's out of scope of the JSON. Does my array need to be passed by reference or something? I'm looking to take the data and put it into a UITableView, but so far nothing is showing.



override func viewDidLoad() {
super.viewDidLoad()

navigationItem.title = "Pokemon"
navigationController?.navigationBar.prefersLargeTitles = true
loadJSON()
print(pokemons.count) //Prints 0
tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellId)
}

override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let label = UILabel()
label.text = "By Id"
label.backgroundColor = UIColor.lightGray
return label
}

override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return pokemons.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath)

let name = pokemons[indexPath.row].name

cell.textLabel?.text = "(name) Section:(indexPath.section) Row:(indexPath.row)"
return cell
}






ios iphone swift






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share|improve this question










asked Nov 25 '18 at 16:28









teachMeSenpaiteachMeSenpai

617




617








  • 1





    loadJSON is asynchronous.

    – rmaddy
    Nov 25 '18 at 16:30











  • hey! sorry I'm not familiar with what that means. Could you explain more?

    – teachMeSenpai
    Nov 25 '18 at 16:35














  • 1





    loadJSON is asynchronous.

    – rmaddy
    Nov 25 '18 at 16:30











  • hey! sorry I'm not familiar with what that means. Could you explain more?

    – teachMeSenpai
    Nov 25 '18 at 16:35








1




1





loadJSON is asynchronous.

– rmaddy
Nov 25 '18 at 16:30





loadJSON is asynchronous.

– rmaddy
Nov 25 '18 at 16:30













hey! sorry I'm not familiar with what that means. Could you explain more?

– teachMeSenpai
Nov 25 '18 at 16:35





hey! sorry I'm not familiar with what that means. Could you explain more?

– teachMeSenpai
Nov 25 '18 at 16:35












1 Answer
1






active

oldest

votes


















1














You either need



self.pokemons.append(load)
DispatchQueue.main.async {
self.tableView.reloadData()
}


or write a completion





the asynchronous call is something that doesn't go in serial with function written code , but runs asynchronously until it finishes then it notifies it's callback and in your code the asynchronous method is URLSession.shared.dataTask which runs in a background thread (that's why you have to insert DispatchQueue.main.async inside it to refresh the UI ) and leave the serial execution at main thread for sure you can block the main thread until response returns with a method like Data(contentsOf:url) instead of URLSession.shared.dataTask but it's not a good idea






share|improve this answer


























  • thanks for you answer! I'm still not really understanding why that's important. Could you explain!

    – teachMeSenpai
    Nov 25 '18 at 16:41











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1














You either need



self.pokemons.append(load)
DispatchQueue.main.async {
self.tableView.reloadData()
}


or write a completion





the asynchronous call is something that doesn't go in serial with function written code , but runs asynchronously until it finishes then it notifies it's callback and in your code the asynchronous method is URLSession.shared.dataTask which runs in a background thread (that's why you have to insert DispatchQueue.main.async inside it to refresh the UI ) and leave the serial execution at main thread for sure you can block the main thread until response returns with a method like Data(contentsOf:url) instead of URLSession.shared.dataTask but it's not a good idea






share|improve this answer


























  • thanks for you answer! I'm still not really understanding why that's important. Could you explain!

    – teachMeSenpai
    Nov 25 '18 at 16:41
















1














You either need



self.pokemons.append(load)
DispatchQueue.main.async {
self.tableView.reloadData()
}


or write a completion





the asynchronous call is something that doesn't go in serial with function written code , but runs asynchronously until it finishes then it notifies it's callback and in your code the asynchronous method is URLSession.shared.dataTask which runs in a background thread (that's why you have to insert DispatchQueue.main.async inside it to refresh the UI ) and leave the serial execution at main thread for sure you can block the main thread until response returns with a method like Data(contentsOf:url) instead of URLSession.shared.dataTask but it's not a good idea






share|improve this answer


























  • thanks for you answer! I'm still not really understanding why that's important. Could you explain!

    – teachMeSenpai
    Nov 25 '18 at 16:41














1












1








1







You either need



self.pokemons.append(load)
DispatchQueue.main.async {
self.tableView.reloadData()
}


or write a completion





the asynchronous call is something that doesn't go in serial with function written code , but runs asynchronously until it finishes then it notifies it's callback and in your code the asynchronous method is URLSession.shared.dataTask which runs in a background thread (that's why you have to insert DispatchQueue.main.async inside it to refresh the UI ) and leave the serial execution at main thread for sure you can block the main thread until response returns with a method like Data(contentsOf:url) instead of URLSession.shared.dataTask but it's not a good idea






share|improve this answer















You either need



self.pokemons.append(load)
DispatchQueue.main.async {
self.tableView.reloadData()
}


or write a completion





the asynchronous call is something that doesn't go in serial with function written code , but runs asynchronously until it finishes then it notifies it's callback and in your code the asynchronous method is URLSession.shared.dataTask which runs in a background thread (that's why you have to insert DispatchQueue.main.async inside it to refresh the UI ) and leave the serial execution at main thread for sure you can block the main thread until response returns with a method like Data(contentsOf:url) instead of URLSession.shared.dataTask but it's not a good idea







share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 25 '18 at 20:58

























answered Nov 25 '18 at 16:38









Sh_KhanSh_Khan

45.5k51432




45.5k51432













  • thanks for you answer! I'm still not really understanding why that's important. Could you explain!

    – teachMeSenpai
    Nov 25 '18 at 16:41



















  • thanks for you answer! I'm still not really understanding why that's important. Could you explain!

    – teachMeSenpai
    Nov 25 '18 at 16:41

















thanks for you answer! I'm still not really understanding why that's important. Could you explain!

– teachMeSenpai
Nov 25 '18 at 16:41





thanks for you answer! I'm still not really understanding why that's important. Could you explain!

– teachMeSenpai
Nov 25 '18 at 16:41




















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