variable not available in URLSESSION - ios

Question

I am doing in mvvm method.my code as below.
foodModel :-
class foodModel: NSObject {
var name :String!
var city :String!
var imageurl :String!
init?(dictionary :JSONDictionary) {
guard let name = dictionary["name"] as? String,
let imageurl = dictionary["imageurl"] as? String,
let city = dictionary["city"] as? String else {
return
}
self.name = name
self.city = city
self.imageurl = imageurl
}
}
foodDataSourceModel:-
class foodDataSourceModel: NSObject {
var dataListArray:Array<foodModel>? = []
init(array :Array<[String:Any]>?) {
super.init()
var newArray:Array<[String:Any]> = []
if array == nil{
newArray = self.getJsonDataStored1()
}
else{
newArray = array!
}
var datalist:Array<foodModel> = []
for dict in newArray{
let model = foodModel(dictionary: dict)
datalist.append(model!)
}
self.dataListArray = datalist
}
}
typealias dummyDataSource1 = foodDataSourceModel
extension dummyDataSource1{
func getJsonDataStored1() ->Array<Dictionary<String,String>>{
let jsonArray = [["name":"Anjapar","imageurl":"","city":"india"],["name":"Anjapar","imageurl":"","city":"india"]] as Array<Dictionary<String,String>>
return jsonArray
}
}
foodViewModel:-
class foodViewModel: NSObject {
var datasourceModel:foodDataSourceModel
init(withdatasource newDatasourceModel:foodDataSourceModel) {
datasourceModel = newDatasourceModel
}
func datafordisplay(atindex index: Int) -> foodModel {
return datasourceModel.dataListArray![index]
}
func numberOfItemsInSection(section:Int) -> Int {
return (datasourceModel.dataListArray?.count)!
}
func loadData(){
loadFromWebserviceData { (newDataSourceModel) in
self.datasourceModel = newDataSourceModel!
}
}
func loadFromWebserviceData(completion :#escaping (foodDataSourceModel?) -> ()){
let url = URL(string :"http://example.com")!
URLSession.shared.dataTask(with: url) { data, _, _ in
if let data = data {
let json = try! JSONSerialization.jsonObject(with: data, options: [])
//let dictionaries = json as! [JSONDictionary]
let array = json as! Array<[String:Any]>
let newDataSource:foodDataSourceModel = foodDataSourceModel(array: array)
// DispatchQueue.main.async {
//
// }
completion(newDataSource)
}
}.resume()
}
}
foodViewController:-
#IBOutlet private weak var tableView: UITableView!
private var foodViewModel :foodViewModel!
init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?, withViewModel viewModel:foodViewModel) {
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
foodViewModel = viewModel
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func viewDidLoad() {
super.viewDidLoad()
// tableView.register(UINib(nibName: "foodCell", bundle: nil), forCellReuseIdentifier: "cell")
foodViewModel.loadData()
self.tableView .reloadData()
// Do any additional setup after loading the view.
}
// func numberOfSections(in tableView: UITableView) -> Int {
// return restaurtantViewModel.numberOfItemsInSection(section: Int)
// }
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell:UITableViewCell = self.tableView.dequeueReusableCell(withIdentifier: "cell")! as! foodCell
//cell.setRestaurtantData(restaurtant: foodModel)
cell.textLabel?.text = "rtyuiop"
//
return cell
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
/*
}
*/
}
foodCell:-
class foodCell: UITableViewCell {
#IBOutlet weak var name: UILabel!
#IBOutlet weak var city: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
func setRestaurtantData(restaurtant:foodModel)
{
self.name.text = restaurtant.name
self.city.text = restaurtant.city
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
Here output is not getting .I need to display the values in tableview.Showing an error as failed to obtain a cell from dataSource
{
"query": "sandwich",
"results_count": 12,
"page": 1,
"results": [
{
"name": "Caffè Macs",
"coordinates": {
"lat": 37.330576,
"lng": -122.029739
},
"meals": ["breakfast", "lunch", "dinner"]
},
...
]
}
This is the pattern ,so from this i need to get the values as "name","lng" and "lat".
There is some problem in load the data from Json .In the urlsession task -showing as variable not available. please check .How to solve this?

Answer 1

Please update your viewDidLoad(). You must set delegate and datasource of tableview.
First set in class:-
class yourClass: UIViewController,UITableViewDelegate , UITableViewDataSource
Now
override func viewDidLoad() {
super.viewDidLoad()
// tableView.register(UINib(nibName: "foodCell", bundle: nil), forCellReuseIdentifier: "cell")
foodViewModel.loadData()
self.tableView .delegate = self
self.tableview.dataSource = self
self.tableView .reloadData()

Answer 2

When you fetch data from a web service, this is usually done in a asynchronous manner. In your viewDidLoad method, you're updating your table view immediately after the call which starts fetching the data.
override func viewDidLoad() {
...
// Start fetching the data
foodViewModel.loadData()
// Reloading the table view even though the data might not be ready
self.tableView.reloadData()
...
}
You can fix this by passing a callback to your loadData function in your foodViewModel:
func loadData(completion: (() -> ()) {
loadFromWebserviceData { (newDataSourceModel) in
self.datasourceModel = newDataSourceModel!
completion()
}
}
And in your foodViewController, you would then wait to update your table view until the data source is ready to be displayed:
override func viewDidLoad() {
...
foodViewModel.loadData {
self.tableView.reloadData()
}
...
}
While the code above should work, this is just to highlight the problem you're currently facing and therefore, was kept as simple as possible.