UserDefaults with Struct - TableView not displaying data from saved from UserDefaults?

Question

Created Apr ’21

Replies 3

Boosts 0

Views 1.1k

Participants 3

I am having problem displaying data on the table view cell
These are my code:

struct Person: Codable {
var firstName: String
var lastName: String
}

class viewController: UIViewController {

var newPerson = [Person]()

override func viewDidLoad() {

let person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]

let encoder = JSONEncoder()
if let encoded = try? encoder.encode(person) {
UserDefaults.standard.set(encoded, forKey: "savedPerson")
}
}
}

var person = [Person]()

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

func tableView( tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

let cell = tableView.dequeueReusableCell(withIdentifier: "cellID", for: indexPath) as! UITableViewCell

cell.textLabel?.text = person[indexPath.row]

return cell
}

Answered by Claude31 in 670442022

The problem is not UserDefaults but errors in your code (formatted with <> tool):

Code Block struct Person: Codable {
    var firstName: String
    var lastName: String
}
class viewController: UIViewController {
var newPerson = [Person]()
override func viewDidLoad() {
    let person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]
   
    let encoder = JSONEncoder()
    if let encoded = try? encoder.encode(person) {
        UserDefaults.standard.set(encoded, forKey: "savedPerson")
    }
  }
}
var person = [Person]()
func tableView( tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return  person.count
  }
func tableView( tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cellID", for: indexPath) as! UITableViewCell
  cell.textLabel?.text = person[indexPath.row]
  
return cell
}

Line 8, you declare newPerson but never use it. What is it for ?
Line 12, you create person. But it does not exist outside of viewDidLoad.
So line 25, person is empty. Hence return 0. And so, nothing is displayed in TableView.

Some other comments for better readabilty

Names of class should start with Uppercase : class ViewController
person is an array, better name it persons.
Declaration better be at beginning of class.

So, more correct code:

Code Block struct Person: Codable {
    var firstName: String
    var lastName: String
}
class ViewController: UIViewController {
    var newPerson = [Person]()     // <== Where do you use it ?
    var persons = [Person]()          // renamed  
    override func viewDidLoad() {
    // NOT Redeclare HERE let person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]
    person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]  // Now, array is populated
    let encoder = JSONEncoder()
    if let encoded = try? encoder.encode(persons) {
        UserDefaults.standard.set(encoded, forKey: "savedPerson")
    }
  }
}
func tableView( tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return  persons.count
  }
func tableView( tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cellID", for: indexPath) as! UITableViewCell
    cell.textLabel?.text = persons[indexPath.row]
  
   return cell
}

If that works, don't forget to close the thread. Otherwise tell exactly what the remaining problem is and post more code if needed.

Boost

Answer 1

OOPer OP

Apr ’21

Please show full code. Fragments of code do not make sense.
In which class person, tableView(_:numberOfRowsInSection:) and tableView(_:cellForRowAt:) are defined?
How are you filling data into the property person? (Asking about the property person, not about the local variable person.)

One more, please use the Code block feature (icon <>) when you want to show some codes.

1

Answer 2

Claude31 OP

Apr ’21

Accepted Answer

The problem is not UserDefaults but errors in your code (formatted with <> tool):

Code Block struct Person: Codable {
    var firstName: String
    var lastName: String
}
class viewController: UIViewController {
var newPerson = [Person]()
override func viewDidLoad() {
    let person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]
   
    let encoder = JSONEncoder()
    if let encoded = try? encoder.encode(person) {
        UserDefaults.standard.set(encoded, forKey: "savedPerson")
    }
  }
}
var person = [Person]()
func tableView( tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return  person.count
  }
func tableView( tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cellID", for: indexPath) as! UITableViewCell
  cell.textLabel?.text = person[indexPath.row]
  
return cell
}

Line 8, you declare newPerson but never use it. What is it for ?
Line 12, you create person. But it does not exist outside of viewDidLoad.
So line 25, person is empty. Hence return 0. And so, nothing is displayed in TableView.

Some other comments for better readabilty

Names of class should start with Uppercase : class ViewController
person is an array, better name it persons.
Declaration better be at beginning of class.

So, more correct code:

Code Block struct Person: Codable {
    var firstName: String
    var lastName: String
}
class ViewController: UIViewController {
    var newPerson = [Person]()     // <== Where do you use it ?
    var persons = [Person]()          // renamed  
    override func viewDidLoad() {
    // NOT Redeclare HERE let person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]
    person = [Person(firstName: "Peterson", lastName: "Jota") , Person(firstName: "John", lastName: "Paul")]  // Now, array is populated
    let encoder = JSONEncoder()
    if let encoded = try? encoder.encode(persons) {
        UserDefaults.standard.set(encoded, forKey: "savedPerson")
    }
  }
}
func tableView( tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return  persons.count
  }
func tableView( tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cellID", for: indexPath) as! UITableViewCell
    cell.textLabel?.text = persons[indexPath.row]
  
   return cell
}

If that works, don't forget to close the thread. Otherwise tell exactly what the remaining problem is and post more code if needed.

1

Answer 3

PopOutTuts OP

Apr ’21

Thank you so much. It works

0