Grouped sections not displaying in tableview - ios

Question

My entire table view is being written programmatically and the data is coming from JSON. I am trying to group the cells by the customer the code seems to be correct but no sections are showing up at all.
Here is the code:
Portfolios.swift
import UIKit
struct Portfolios: Codable {
let customer, serial, rma, model: String
let manufacturer: String
}
PortfolioController.swift
import UIKit
class PortfolioController: UITableViewController {
var portfolios = [Portfolios]()
var portfoliosDic = [String:[Portfolios]]()
override func viewDidLoad() {
super.viewDidLoad()
navigationController?.navigationBar.prefersLargeTitles = true
view.backgroundColor = UIColor.blue
navigationItem.title = "Customer"
fetchJSON()
}
func fetchJSON(){
let urlString = "https://www.example.com/example/example.php"
guard let url = URL(string: urlString) else { return }
URLSession.shared.dataTask(with: url) { (data, _, error) in
DispatchQueue.main.async {
if let error = error {
print("Failed to fetch data from url", error)
return
}
guard let data = data else { return }
do {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let res = try JSONDecoder().decode([Portfolios].self, from: data)
self.portfoliosDic = Dictionary(grouping: res, by: { $0.customer})
DispatchQueue.main.async {
self.tableView.reloadData()
}
self.portfolios = try decoder.decode([Portfolios].self, from: data)
self.tableView.reloadData()
} catch let jsonError {
print("Failed to decode json", jsonError)
}
}
}.resume()
}
override func numberOfSections(in tableView: UITableView) -> Int {
return portfoliosDic.keys.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let keys = Array(portfoliosDic.keys)
let item = portfoliosDic[keys[section]]!
return item.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: .subtitle, reuseIdentifier: "cellId")
let keys = Array(portfoliosDic.keys)
let arr = portfoliosDic[keys[indexPath.section]]!
let customer = arr[indexPath.row]
let titleStr = [customer.serial, customer.manufacturer, customer.model].compactMap { $0 }.joined(separator: " - ")
//cell.textLabel?.text = titleStr
print(titleStr)
// Get references to labels of cell
cell.textLabel!.text = customer.serial
return cell
}
}
UPDATE:
Because it is a UIViewController Xcode told me to remove the override func
and I added #IBOutlet weak var tableView: UITableView!
(The end results is an empty table for some reason)
Using a UITableViewController instead:
import UIKit
class CustomerViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
var sections = [Section]()
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cellId")
navigationController?.navigationBar.prefersLargeTitles = true
fetchJSON()
}
func fetchJSON(){
let urlString = "https://www.example.com/example/example.php"
guard let url = URL(string: urlString) else { return }
URLSession.shared.dataTask(with: url) { (data, _, error) in
DispatchQueue.main.async {
if let error = error {
print("Failed to fetch data from url", error)
return
}
guard let data = data else { return }
do {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let res = try decoder.decode([Portfolios].self, from: data)
let grouped = Dictionary(grouping: res, by: { $0.customer })
let keys = grouped.keys.sorted()
self.sections = keys.map({Section(name: $0, items: grouped[$0]!)})
DispatchQueue.main.async {
self.tableView.reloadData()
}
} catch {
print("Failed to decode json", error)
}
}
}.resume()
}
func numberOfSections(in tableView: UITableView) -> Int {
return sections.count
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let section = sections[section]
return section.items.count
}
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return sections[section].name
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cellId", for: indexPath)
let section = sections[indexPath.section]
let item = section.items[indexPath.row]
let titleStr = "\(item.serial) - \(item.manufacturer) - \(item.model)"
cell.textLabel!.text = titleStr
return cell
}
}

Answer 1

First of all why do you decode the JSON twice?
No sections are displayed because the method titleForHeaderInSection is not implemented.
The code is not reliable anyway because the order of the sections is not guaranteed. I recommend to create another struct for the sections.
struct Section {
let name : String
let items : [Portfolios]
}
struct Portfolios: Decodable {
let customer, serial, rma, model: String
let manufacturer: String
}
Delete portfolios and portfoliosDic and declare the data source array
var sections = [Section]()
Group the JSON, sort the keys and map the dictionaries to Section instances
do {
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let res = try decoder.decode([Portfolios].self, from: data)
let grouped = Dictionary(grouping: res, by: { $0.customer })
let keys = grouped.keys.sorted()
self.sections = keys.map({Section(name: $0, items: grouped[$0]!)})
DispatchQueue.main.async {
self.tableView.reloadData()
}
} catch {
print("Failed to decode json", error)
}
The table view datasource and delegate methods are
override func numberOfSections(in tableView: UITableView) -> Int {
return sections.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let section = sections[section]
return section.items.count
}
override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return sections[section].name
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cellId", for: indexPath)
let section = sections[indexPath.section]
let item = section.items[indexPath.row]
let titleStr = "\(item.serial) - \(item.manufacturer) - \(item.model)"
cell.textLabel!.text = titleStr
return cell
}
Note:
Always dequeue cells in cellForRowAt