I'm using a UITabBarController to create a contact list, but when I'm trying to save the array to load the data when I restart the app is giving me problems where the data isn't displayed. I'm using UserDefaults to save the data and the restore when the app is restarted.
In this code I sent data from a textfield to the array named list.
import UIKit
class NewContactoViewController: UIViewController {
#IBOutlet weak var input: UITextField!
#IBAction func add(_ sender: Any) {
if (input.text != "") {
list.append(input.text!)
UserDefaults.standard.set(list, forKey: "SavedValue")
input.text = ""
}
}
}
In this code I'm printing the data in a table, and trying to save it with user defaults.
import UIKit
var list = [String]()
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
if let x = UserDefaults.standard.object(forKey: "SavedValue") as? String {
return (x.count)
}
return (0)
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "cell")
if let x = UserDefaults.standard.dictionary(forKey: "SavedValue") as? String {
cell.textLabel?.text = [x[indexPath.row]]
}
return(cell)
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == UITableViewCellEditingStyle.delete {
list.remove(at: indexPath.row)
myTableView.reloadData()
}
}
override func viewDidAppear(_ animated: Bool) {
myTableView.reloadData()
}
#IBOutlet weak var myTableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
}
}
You are saving an array of strings but you are reading a single string (or even a dictionary) which obviously cannot work. There is a dedicated method stringArray(forKey to read a string array.
Apart from the issue never read from UserDefaults to populate the data source in the table view data source and delegate methods, do it in viewDidLoad or viewWillAppear for example
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if let savedArray = UserDefaults.standard.stringArray(forKey: "SavedValue") {
list = savedArray
}
myTableView.reloadData()
}
Put the data source array in the view controller. A global variable as data source is very bad programming habit.
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
var list = [String]()
...
In numberOfRowsInSection return the number of items in list and return is not a function, there are no parentheses
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return list.count
}
Same in cellForRow. Get the item from list and use reusable cells and again, return is not a function.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel?.text = list[indexPath.row]
return cell
}
Note :
Consider that UserDefaults is the wrong place to share data between view controllers. Use segues, callbacks or protocol / delegate.
Related
when I tried to use this code to get the images, I'm not getting list list of images
import UIKit
class ViewController: UITableViewController {
var pictures = [String]()
override func viewDidLoad() {
super.viewDidLoad()
let fm = FileManager.default
let path = Bundle.main.resourcePath!
let items = try! fm.contentsOfDirectory(atPath: path)
for item in items {
if item.hasPrefix("nssl"){
//load pics
pictures.append(item)
}
}
print(pictures)
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return pictures.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Picture", for: indexPath)
cell.textLabel?.text = pictures[indexPath.row]
return cell
}
}
I have an empty array set as a global variable that is populated with array items from a tableview. This is used to populate another tableview. This data needs to persist so that when the user returns to the app, their tableview data is in the same state they left it, i.e. populate with data from the array.
Though I've looked for dozens of tutorials and examples. I've also hacked at it myself to make it work and every time I reload the app, the array is empty. How can I get that global variable array to hold onto it's array data?
var sharedData = [String]()
This is my 1st VC where I have setup functions for the UserDefaults. And I've executed my saveArray() func every time a change is made to the array. I've then executed retrieveArray() func every time I need to load from the array.
import UIKit
var sharedData = [String]()
struct Keys {
static let arrayKey = "arrayKey"
}
let defaults = UserDefaults.standard
func saveArray() {
defaults.set(sharedData, forKey: Keys.arrayKey)
}
func retrieveArray() {
var savedData = defaults.object(forKey: Keys.arrayKey) as? [String] ?? []
savedData.append(contentsOf: sharedData)
}
class ViewController: UIViewController {
var effect:UIVisualEffect!
#IBOutlet weak var searchBar: UISearchBar!
#IBOutlet var tableView: UITableView!
#IBOutlet weak var activityIndicator: UIActivityIndicatorView!
#IBOutlet weak var visualEffectView: UIVisualEffectView!
let materialData = ["One", "Two", "Three", "Four"]
var searchMaterial = [String]()
var searching = false
#IBAction func favoritesButtonArrayUpdate(_ sender: UIBarButtonItem) {
print(sharedData)
}
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
saveArray()
retrieveArray()
print(sharedData)
}
extension ViewController: UITableViewDelegate {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
print(self.materialData[indexPath.row], "selected!")
}
func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
let favorite = UITableViewRowAction(style: .default, title: "Favorite") { (action, indexPath) in
var data: String
if self.searching {
data = self.searchMaterial[indexPath.row]
} else {
data = self.materialData[indexPath.row]
}
sharedData.append(data)
saveArray()
print(sharedData)
}
favorite.backgroundColor = UIColor.orange
return [favorite]
}
}
This is my 2nd VC which displays the array data stored in the global variable array sharedData. I've again added all the func when making changes to the array and pulling data from the array.
import UIKit
class FavoritesViewController: UIViewController {
#IBOutlet var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
saveArray()
retrieveArray()
}
}
extension FavoritesViewController: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
retrieveArray()
return sharedData.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
retrieveArray()
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
cell.textLabel?.numberOfLines = 0
cell.textLabel?.text = sharedData[indexPath.row]
return cell
}
func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
return true
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
sharedData.remove(at: indexPath.row)
saveArray()
tableView.beginUpdates()
tableView.deleteRows(at: [indexPath], with: .automatic)
tableView.endUpdates()
}
}
}
The problem could be here:
let savedData: [String] = userDefaults.object(forKey: "arrayKey") as? [String] ?? []
Try changing it with:
let savedData: [String] = userDefaults?.object(forKey: "arrayKey") as? [String] ?? []
This is because UserDefaults must be unwrapped to refer to member object. Give it a try
Based on MrHim recommendations I removed the saveArray and retrieveArray func from the viewDidLoad of my first VC and left retrieveArray in viewDidLoad of my second VC. Having saveArray in my viewDidLoads was overwriting the array with empty data. I then needed to retrieve the array data in the proper place in my second VC. Then in my numberOfRowsInSection I removed retrieveArray.
I have two viewControllers one called programlist that displays the list of tiles and populates a a suitable view.
the second viewController inputs the data. Issues implementing the callback due to an error in the prepareForsegue function. Getting the error "Instance member 'callback' cannot be used on type 'addWorkout'"
viewController 1 aka Programlist:
import UIKit
struct Item: Codable {
var title: String
var others: [String]
}
class ProgramList: UIViewController, UITableViewDataSource, UITableViewDelegate{
var Programs = [Item]()
#IBOutlet weak var programTableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
load()
}
//saving current state of programs array
func save() {
guard let data = try? JSONEncoder().encode(Programs) else { return }
UserDefaults.standard.set(data, forKey: "notes")
}
//loading saved program array
func load() {
guard let loadedData = UserDefaults.standard.data(forKey: "notes") else { return }
do {
Programs = try JSONDecoder().decode([Item].self, from: loadedData)
programTableView.reloadData()
} catch { print(error) }
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return Programs.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TableViewCell
cell.programTitle.text = Programs[indexPath.row].title
return cell
}
//Removing Item by swipping left & saving this newly established array
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == UITableViewCell.EditingStyle.delete {
Programs.remove(at: indexPath.row)
programTableView.reloadData()
save()
}
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "toAddPage"{
workoutController.callback = { [weak self] string in
let entered = Item(title: string, others: ["hi"])
self?.programs.append(entered)
let indexPath = IndexPath(row: self?.programs.count - 1, section: 0)
self?.tableView.insertRows(at: [indexPath], with: .automatic)
self?.save()
}
}
}
}
}
}
viewController 2 aka addWorkout:
import UIKit
class addWorkout: UIViewController {
#IBOutlet weak var workoutTitle: UITextField!
var callback : ((String) -> Void)?
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func saveWorkoutTitle(_ sender: Any) {
if !workoutTitle.text!.isEmpty {
callback?(workoutTitle.text!)
}
}
}
The main mistake is you are trying to save an array of Item – which is not supported anyway – to UserDefaults and read an array of String. That's a clear type mismatch.
To be able to save an array of a custom struct to UserDefaults adopt Codable to save the struct as JSON.
struct Item : Codable {
var title: String
var others: [String]
}
Further it's a very bad practice to declare a data source array outside of any class.
This is the ProgramList class with adjusted load and save methods and the data source array inside the class. The method viewDidAppear is not needed.
class ProgramList: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var programTableView: UITableView!
var programs = [Item]()
override func viewDidLoad() {
super.viewDidLoad()
load()
}
//saving current state of programs array
func save() {
guard let data = try? JSONEncoder().encode(programs) else { return }
UserDefaults.standard.set(data, forKey: "notes")
}
//loading saved program array
func load() {
guard let loadedData = UserDefaults.standard.data(forKey: "notes") else { return }
do {
programs = try JSONDecoder().decode([Item].self, from: loadedData)
programTableView.reloadData()
} catch { print(error) }
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return programs.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TableViewCell
cell.programTitle.text = programs[indexPath.row].title
return cell
}
//Removing Item by swipping left & saving this newly established array
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
programs.remove(at: indexPath.row)
programTableView.deleteRows(at: [indexPath], with: .automatic)
save()
}
}
}
To share data between controllers use a closure as callback and pass the string
class AddWorkout: UIViewController {
#IBOutlet weak var workoutTitle: UITextField!
var callback : ((String) -> Void)?
#IBAction func saveWorkoutTitle(_ sender: Any) {
if !workoutTitle.text!.isEmpty {
callback?(workoutTitle.text!)
}
}
}
Back in ProgramList controller assign a closure to the callback property in prepareForSegue (or right before presenting the controller)
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "toAddPage" {
let workoutController = segue.destination as! AddWorkout
workoutController.callback = { string in
let entered = Item(title: string, others: ["hi"])
self.programs.append(entered)
let indexPath = IndexPath(row: self.programs.count - 1, section: 0)
self.tableView.insertRows(at: [indexPath], with: .automatic)
self.save()
}
}
}
I need to add data to an array.
However, with my code: it overrides the data instead of appending it?
import UIKit
class Productreview: UIViewController, UITableViewDataSource, UITableViewDelegate {
var Item:String! //Data from another viewcontroller
var list:[String] = [] //The array
//Update func
func updatelist() {
var listupdate = list
listupdate.append(Item)
list = listupdate
}
override func viewDidLoad() {
super.viewDidLoad()
updatelist()
// Do any additional setup after loading the view.
}
//Sets the tableView-data
#IBOutlet weak var tableView: UITableView!
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return (list.count)
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell = UITableViewCell(style: UITableViewCell.CellStyle.default, reuseIdentifier: "cell")
cell.textLabel?.text = list[indexPath.row]
return(cell)
}
}
This looks redundant.
func updatelist() {
var listupdate = list
listupdate.append(Item)
list = listupdate
}
Why not just append it directly to the list?
func updatelist() {
list.append(Item)
}
And i see that you are updating the list in viewDidLoad. So there will only be one String in the array. So my suspicion is that you create a new instance of ProductReview every time and not save the previous list anywhere. So what you need to do is save the list every time you append to it, but not inside ProductReview.
Now that i think about it. What is the use of the variable Item when you are only using it to append the value to the list in viewDidLoad?
Solution:
So, my suggestion would be that you form the list and pass the list to the ProductReview instance.
Sidenote: Like #AshelyMills pointed out in the comments, use lowerCamelCase for variables in Swift.
import UIKit
class Productreview: UIViewController, UITableViewDataSource, UITableViewDelegate {
// You have to write lowercase . Not write 'Item'
var item:String! //Data from another viewcontroller
var list:[String] = [] //The array
override func viewDidLoad() {
super.viewDidLoad()
// You have to define delegate and datasource
self.tableView.delegate = self
self.tableView.dataSource = self
updatelist()
// Do any additional setup after loading the view.
}
//Update func
func updatelist() {
var listupdate = list
listupdate.append(item)
list = listupdate
self.tableView.reloadData() // Dont forget this for showing elements.
}
//Sets the tableView-data
#IBOutlet weak var tableView: UITableView!
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return list.count
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
let cell = UITableViewCell(style: UITableViewCell.CellStyle.default, reuseIdentifier: "cell")!
cell.textLabel?.text = list[indexPath.row]
return cell
}
}
I'm pulling data from Parse into an array but need a way to reference that specific object directly for making changes to the data on the server (ex: deleting a specific entry off the app and having it delete on the server). Previously I was using an array filled with a PFQuery, which worked for pulling data down but not for making changes back up. I think creating a dictionary with [objectID : string of data needed] would work, so each data set currently in the array would always be paired directly to it's identifier. My issue is pulling both sets of data down (objectID and string of data) and matching them up in the dictionary. Any advice or help?
I changed the original array to a dictionary in the cellContent variable but otherwise the code is still set up for an array.
Thanks!
import UIKit
import Parse
var segueWorker = ""
class MyWorkersViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
var cellContent = [String: String]()
#IBAction func backButton(_ sender: Any) {
navigationController?.popViewController(animated: true)
performSegue(withIdentifier: "workersToMyFarm", sender: self)
}
#IBOutlet weak var tableView: UITableView!
internal func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return cellContent.count
}
internal func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "Cell")
cell.textLabel?.text = cellContent[indexPath.row]
return cell
}
override func viewDidAppear(_ animated: Bool) {
// Do any additional setup after loading the view.
self.cellContent.removeAll()
let query = PFQuery(className: "Workers")
query.findObjectsInBackground(block: { (objects1, error) in
if error != nil {
print(error!)
} else {
query.whereKey("username", equalTo: PFUser.current()?.username)
query.findObjectsInBackground(block: { (objects2, error) in
for object in objects2! {
self.cellContent.append(object["workerName"] as! String)
self.cellContent.sort()
self.tableView.reloadData()
}
}
)}
}
)}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == UITableViewCellEditingStyle.delete {
cellContent.remove(at: indexPath.row)
tableView.reloadData()
}
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let indexPath = tableView.indexPathForSelectedRow
let currentCell = tableView.cellForRow(at: indexPath!)!
segueWorker = (currentCell.textLabel!.text!)
performSegue(withIdentifier: "toAddWorkers", sender: self)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
Took some tinkering but finally got it to work by spreading out the variables and finally building the dictionary once I had all variables created. Also, had a lot of trouble with getting the objectId from Parse but seems to be working by simply calling object.objectId.
Code below for reference:
self.cellContent.removeAll()
let query = PFQuery(className: "Workers")
query.findObjectsInBackground(block: { (objects1, error) in
if error != nil {
print(error!)
} else {
query.whereKey("username", equalTo: PFUser.current()?.username)
query.findObjectsInBackground(block: { (objects2, error) in
for object in objects2! {
self.cellContent.append(object["workerName"] as! String)
// Needs to be objectId
let objectKey = object.objectId
let objectValue = object["workerName"] as! String
self.cellContentDict[objectKey!] = objectValue
print(self.cellContentDict)
self.cellContent.sort()
self.tableView.reloadData()