How to use preference from other didSet variable in custom Cell? - ios

I have a custom cell for a collectionView and inside I have 3 didSet variables. My problem is that I need to use 1 preference from each didSet to display on a label but I can't figure out a way to do so. Any suggestions?
class VideosCell: UICollectionViewCell {
var playlistDataFromAPI: playListsnippet? {
didSet{
guard let pubDate = playlistDataFromAPI?.snippet.publishedAt else {return}
}
}
var videoSnippet: videoSnippet? {
didSet{
guard let duration = videoSnippet?.contentDetails.duration else {return}
}
}
var channelData: channelSnippet? {
didSet{
guard let channelName = channelData?.snippet.title else {return}
}
}
Now I want to use pubDate, duration, and channelName all together to display on a label such as: label.text = channelName, duration, pubDate
Thank you very much for your help!

In your UIView or UIViewController subclass, I recommend declaring a nested struct called Content that has properties for any values you need to display.
Then have an instance var of type Content, and you can access its properties from anywhere in the class.
Bundling all such properties together has several nice benefits, such as being able to export all the current stuff the user is seeing in one line of code to JSON for logging (if you make it Codable), cleaner testing, etc.

Related

What is NSDiffableDataSourceSnapshot `reloadItems` for?

I'm having difficulty finding the use of NSDiffableDataSourceSnapshot reloadItems(_:):
If the item I ask to reload is not equatable to an item that is already present in the data source, I crash with:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Attempted to reload item identifier that does not exist in the snapshot: ProjectName.ClassName
But if the item is equatable to an item that is already present in the data source, then what's the point of "reloading" it?
You might think the answer to the second point is: well, there might be some other aspect of the item identifier object that is not part of its equatability but does reflect into the cell interface. But what I find is that that's not true; after calling reloadItems, the table view does not reflect the change.
So when I want to change an item, what I end up doing with the snapshot is an insert after the item to be replaced and then a delete of the original item. There is no snapshot replace method, which is what I was hoping reloadItems would turn out to be.
(I did a Stack Overflow search on those terms and found very little — mostly just a couple of questions that puzzled over particular uses of reloadItems, such as How to update a table cell using diffable UITableView. So I'm asking in a more generalized form, what practical use has anyone found for this method?)
Well, there's nothing like having a minimal reproducible example to play with, so here is one.
Make a plain vanilla iOS project with its template ViewController, and add this code to the ViewController.
I'll take it piece by piece. First, we have a struct that will serve as our item identifier. The UUID is the unique part, so equatability and hashability depend upon it alone:
struct UniBool : Hashable {
let uuid : UUID
var bool : Bool
// equatability and hashability agree, only the UUID matters
func hash(into hasher: inout Hasher) {
hasher.combine(uuid)
}
static func ==(lhs:Self, rhs:Self) -> Bool {
lhs.uuid == rhs.uuid
}
}
Next, the (fake) table view and the diffable data source:
let tableView = UITableView(frame: .zero, style: .plain)
var datasource : UITableViewDiffableDataSource<String,UniBool>!
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
self.datasource = UITableViewDiffableDataSource<String,UniBool>(tableView: self.tableView) { tv, ip, isOn in
let cell = tv.dequeueReusableCell(withIdentifier: "cell", for: ip)
return cell
}
var snap = NSDiffableDataSourceSnapshot<String,UniBool>()
snap.appendSections(["Dummy"])
snap.appendItems([UniBool(uuid: UUID(), bool: true)])
self.datasource.apply(snap, animatingDifferences: false)
}
So there is just one UniBool in our diffable data source and its bool is true. So now set up a button to call this action method which tries to toggle the bool value by using reloadItems:
#IBAction func testReload() {
if let unibool = self.datasource.itemIdentifier(for: IndexPath(row: 0, section: 0)) {
var snap = self.datasource.snapshot()
var unibool = unibool
unibool.bool = !unibool.bool
snap.reloadItems([unibool]) // this is the key line I'm trying to test!
print("this object's isOn is", unibool.bool)
print("but looking right at the snapshot, isOn is", snap.itemIdentifiers[0].bool)
delay(0.3) {
self.datasource.apply(snap, animatingDifferences: false)
}
}
}
So here's the thing. I said to reloadItems with an item whose UUID is a match, but whose bool is toggled: "this object's isON is false". But when I ask the snapshot, okay, what have you got? it tells me that its sole item identifier's bool is still true.
And that is what I'm asking about. If the snapshot is not going to pick up the new value of bool, what is reloadItems for in the first place?
Obviously I could just substitute a different UniBool, i.e. one with a different UUID. But then I cannot call reloadItems; we crash because that UniBool is not already in the data. I can work around that by calling insert followed by remove, and that is exactly how I do work around it.
But my question is: so what is reloadItems for, if not for this very thing?
(I've filed a bug on the behavior demonstrated in the question, because I don't think it's good behavior. But, as things stand, I think I can provide a guess as to what the idea is intended to be.)
When you tell a snapshot to reload a certain item, it does not read in the data of the item you supply! It simply looks at the item, as a way of identifying what item, already in the data source, you are asking to reload.
(So, if the item you supply is Equatable to but not 100% identical to the item already in the data source, the "difference" between the item you supply and the item already in the data source will not matter at all; the data source will never be told that anything is different.)
When you then apply that snapshot to the data source, the data source tells the table view to reload the corresponding cell. This results in the data source's cell provider function being called again.
OK, so the data source's cell provider function is called, with the usual three parameters — the table view, the index path, and the data from the data source. But we've just said that the data from the data source has not changed. So what is the point of reloading at all?
The answer is, apparently, that the cell provider function is expected to look elsewhere to get (at least some of) the new data to be displayed in the newly dequeued cell. You are expected to have some sort of "backing store" that the cell provider looks at. For example, you might be maintaining a dictionary where the key is the cell identifier type and the value is the extra information that might be reloaded.
This must be legal, because by definition the cell identifier type is Hashable and can therefore serve as a dictionary key, and moreover the cell identifiers must be unique within the data, or the data source would reject the data (by crashing). And the lookup will be instant, because this is a dictionary.
Here's a complete working example you can just copy and paste right into a project. The table portrays three names along with a star that the user can tap to make star be filled or empty, indicating favorite or not-favorite. The names are stored in the diffable data source, but the favorite status is stored in the external backing store.
extension UIResponder {
func next<T:UIResponder>(ofType: T.Type) -> T? {
let r = self.next
if let r = r as? T ?? r?.next(ofType: T.self) {
return r
} else {
return nil
}
}
}
class TableViewController: UITableViewController {
var backingStore = [String:Bool]()
var datasource : UITableViewDiffableDataSource<String,String>!
override func viewDidLoad() {
super.viewDidLoad()
let cellID = "cell"
self.tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellID)
self.datasource = UITableViewDiffableDataSource<String,String>(tableView:self.tableView) {
tableView, indexPath, name in
let cell = tableView.dequeueReusableCell(withIdentifier: cellID, for: indexPath)
var config = cell.defaultContentConfiguration()
config.text = name
cell.contentConfiguration = config
var accImageView = cell.accessoryView as? UIImageView
if accImageView == nil {
let iv = UIImageView()
iv.isUserInteractionEnabled = true
let tap = UITapGestureRecognizer(target: self, action: #selector(self.starTapped))
iv.addGestureRecognizer(tap)
cell.accessoryView = iv
accImageView = iv
}
let starred = self.backingStore[name, default:false]
accImageView?.image = UIImage(systemName: starred ? "star.fill" : "star")
accImageView?.sizeToFit()
return cell
}
var snap = NSDiffableDataSourceSnapshot<String,String>()
snap.appendSections(["Dummy"])
let names = ["Manny", "Moe", "Jack"]
snap.appendItems(names)
self.datasource.apply(snap, animatingDifferences: false)
names.forEach {
self.backingStore[$0] = false
}
}
#objc func starTapped(_ gr:UIGestureRecognizer) {
guard let cell = gr.view?.next(ofType: UITableViewCell.self) else {return}
guard let ip = self.tableView.indexPath(for: cell) else {return}
guard let name = self.datasource.itemIdentifier(for: ip) else {return}
guard let isFavorite = self.backingStore[name] else {return}
self.backingStore[name] = !isFavorite
var snap = self.datasource.snapshot()
snap.reloadItems([name])
self.datasource.apply(snap, animatingDifferences: false)
}
}
Based on your new example code, I agree, it looks like a bug. When you add a reloadItems to a snapshot it correctly triggers the datasource closure to request an updated cell, but the IdentifierType item that is passed to the closure is the original, not the new value that was provided with the reloadItems call.
If I changed your UniBool struct to a class so that it is a reference rather than a value type, then things worked as expected (since there is now a single instance of a UniBool rather than a new one with the same identifier).
It seems at the moment there are a couple of possible work-arounds:
Use a reference rather than a value type for the IdentifierType
Use an additional backing store, such as an array, and access it via indexPath in the datasource closure.
I don't think that either of these are ideal.
Interestingly, after I changed UniBool to a class, I tried creating a new instance of UniBool that had the same uuid as the existing instance and reloading that; The code crashed with an exception stating Invalid item identifier specified for reload; This doesn't sound right to me; Only the hashValue should matter, not the actual object reference. Both the original and the new objects had the same hashValue and == returned true.
Original answer
reloadItems works, but there are two important points:
You must start with the datasource's current snapshot and call reloadItems on that. You can't create a new snapshot.
You can't rely on the item passed to the CellProvider closure for anything other than the identifier - It doesn't represent the most recent data from your backing model (array).
Point 2 means that you need to use the provided indexPath or item.id to obtain your updated object from your model.
I created a simple example that displays the current time in a table row; This is the data source struct:
struct RowData: Hashable {
var id: UUID = UUID()
var name: String
private let possibleColors: [UIColor] = [.yellow,.orange,.cyan]
var timeStamp = Date()
func hash(into hasher: inout Hasher) {
hasher.combine(self.id)
}
static func ==(lhs: RowData, rhs: RowData) -> Bool {
return lhs.id == rhs.id
}
}
Note that despite the hash function only using the id property it is also necessary to override == or you will get a crash with an invalid identifier when you attempt to reload the row.
Each second a random selection of rows are reloaded. When you run the code you see that the time is updated on those randomly selected rows.
This is the code that uses reloadItems:
self.timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { (timer) in
guard let datasource = self.tableview.dataSource as? UITableViewDiffableDataSource<Section,RowData> else {
return
}
var snapshot = datasource.snapshot()
var rowIdentifers = Set<RowData>()
for _ in 0...Int.random(in: 1...self.arrItems.count) {
let randomIndex = Int.random(in: 0...self.arrItems.count-1)
self.arrItems[randomIndex].timeStamp = Date()
rowIdentifers.insert(self.arrItems[randomIndex])
}
snapshot.reloadItems(Array(rowIdentifers))
datasource.apply(snapshot)
}
I posted the same question, not realising. I got this working by firstly converting my model to classes. Then calling 'applySnapshot' after calling 'reloadItems'.
func toggleSelectedStateForItem(at indexPath: IndexPath, animate: Bool = true) {
let item = dataSource.itemIdentifier(for: indexPath)!
var snapshot = dataSource.snapshot()
item.isSelected = !item.isSelected
snapshot.reloadItems([item])
dataSource.apply(snapshot)
}
I found (via Swift Senpai) that the way you update these diffabledatasource depends on if your model is a class (pass by reference) or struct (pass by value). In the pass by reference you can take the item, update it, then reload the item:
// Model is a class compliant with Hasable and Equatable, name String property
guard let selectedItem = dataSource.itemIdentifier(for: indexPath) else { return}
// modify item
selectedItem.name = "new name"
// update the snapshot
var newSnapShot = dataSource.snapshot()
newSnapshot.reloadItems([selectedItem])
dataSource.apply(newSnapshot)
So the above code will work with a model that is a class (the class needs to explicitly implement hast(into:) and ==(lhs:rhs:)).
On the other hand, a struct requires you to copy the item, update it, then insert the updated item and delete the old item from the snapshot.
// Model is a struct with name String property
guard let selectedItem = dataSource.itemIdentifier(for: indexPath) else { return}
// update the item
var updatedSelectedItem = selectedItem
updatedSelectedItem.name = "new name"
// update snapshot
var newSnapShot = dataSource.snapshot()
newSnapshot.insertItems([updatedSelectedItem], beforeItem: selectedItem)
newSnapshot.deleteItems([selectedItem])
dataSource.apply(newSnapshot)
These worked for me.

Swift NavigationBar Press "Back" to get values, why?

I am using some values to perform some calculations. For testing purposes I show in Label1 a value as string, since it is stored as a string and in Label2 I show a casted value as a Double since I need them at the end as doubles for my calculations.
The weird thing is, that when I access the ViewController the first time it doesn't show any values. But if I go back and klick on it again using the navigation controller it actually works. But I need the values right away cause my original intention is as I said, not showing some labels but rather making some calculations with it.
I made a little gif to show you what the problem is but I have problem with adding photos. Basically what happens is, that I click on the ViewController with the labels and nothing is showed. I go back and press again and the values will be showed in the labels.
Why is that and how can it be showed right away/ used for calculations right away
Thanks for the help. :)
class AHPfinalPreferencesViewController: UIViewController {
var ahpPrios = [AHPPriorityStruct]()
let decoder = JSONDecoder()
#IBOutlet weak var label1: UILabel!
#IBOutlet weak var label2: UILabel!
let ajkpXc = globaLajkpXc
let ajkpXijr = globaLajkpXijr
let valueA = globaLajkpXc
let valueB = Double(globaLajkpXijr)
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
UserService.ahpPref(for: User.current) { (ahpPrios) in
self.ahpPrios = ahpPrios
print("This is our AHP PRIOS", ahpPrios)
for ahpPrio in ahpPrios {
print(ahpPrio)
}
print("this is the global ajk. ", self.ajkpXc)
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Mark: - Get Data
label1.text = valueA
label2.text = "\(String(describing: valueB))"
// MARK: - Set Values for calculation
// setValues()
// ahpCalculation()
}
}
Could it be because of the globalVariables? I know that it is not the right way to do it but for my purposes its absolutely "okay"
import Foundation
import FirebaseAuth.FIRUser
import FirebaseDatabase
import FirebaseUI
import FirebaseAuth
import CodableFirebase
var globaLajkpXc: String = String()
var globaLajkpXijr: String = String()
var globaLajkpXqpa: String = String()
struct UserService {
static func ahpPref(for user: User, completion: #escaping ([AHPPriorityStruct]) -> Void) {
let ref = Database.database().reference().child("AHPRatings").child(user.uid)
ref.observe(DataEventType.value, with: { snapshot in
guard let value = snapshot.value else { return }
do {
let ahpPrios = try FirebaseDecoder().decode(AHPPriorityStruct.self, from: value)
print(ahpPrios)
// MARK: - lets store the values in the actual constants :)
let ajkpXc = ahpPrios.ajkpXc
let ajkpXijr = ahpPrios.ajkpXijr
let ajkpXqpa = ahpPrios.ajkpXqpa
globaLajkpXc = ajkpXc ?? "no Value"
globaLajkpXijr = ajkpXijr ?? "no Value"
globaLajkpXqpa = ajkpXqpa ?? "no Value"
} catch let error {
print(error)
}
})
}
}
[1]: https://i.stack.imgur.com/VKxaE.png
You are calling UserService's ahpPref in your controller's viewWillAppear. BUT you are attempting to put your valueA (globaLajkpXc's value) to your label in your controller's viewDidLoad.
So what does that mean? Do you know which of these two controller's life cycle method gets called and when they do get called?
To solve your problem, have your label assigning value code
label1.text = globaLajkpXc
move in the completion block of your ahpPref (in the viewWillAppear).
Here's the Apple's documentation about the UIViewController's lifecycle: https://developer.apple.com/library/archive/referencelibrary/GettingStarted/DevelopiOSAppsSwift/WorkWithViewControllers.html
Also, below this line: globaLajkpXqpa = ajkpXqpa ?? "no Value"
add your completion call, like:
completion([ahpPrios]).
This should make my answer above work.

How to retrieve UseDefault saved data from another ViewController

I have 2 ViewControllers, one displays the UI and the 2nd one displays a segmented control used as a settings button. Im using the below code to save the segmented control state:
UserDefaults.standard.set(selectorLabel.selectedSegmentIndex, forKey: "stateSelected")
I then retrieve that usedefault on the viewdidload method:
if let value = UserDefaults.standard.value(forKey: "stateSelected"){
let selectedIndex = value as! Int
selectorLabel.selectedSegmentIndex = selectedIndex
}
So far this works as intended and the state of the segmented controlled is loaded properly each app load.
The segmented control has two text titles - one is "LBs & INs" and the second is "KGs & CMs".
How would I save those two segmented control text titles as UserDefaults and then call them on the first ViewController to set two labels on the viewdidload?
Define a model to represent data you want to store and restore:
struct SegmentedControlState: Codable {
let selectedIndex: Int
let titles: [String]
}
Initialize a model, encode and store it somewhere (like user default):
func saveState(of segmentedControl: UISegmentedControl) {
let state = SegmentedControlState(
selectedIndex: segmentedControl.selectedSegmentIndex,
titles: (0..<segmentedControl.numberOfSegments).map { segmentedControl.titleForSegment(at: $0) ?? ""})
let plist = try! PropertyListEncoder().encode(state)
UserDefaults.standard.set(plist, forKey: "SegmentedControlState")
//UserDefaults.standard.synchronize() //if targeting older iOS
}
for restoring, you should reverse the order like this:
func loadState(on segmentedControl: UISegmentedControl) {
guard let plist = UserDefaults.standard.value(forKey: "SegmentedControlState") as? Data else { return }
let state = try! PropertyListDecoder().decode(SegmentedControlState.self, from: plist)
for element in state.titles.enumerated() {
segmentedControl.setTitle(element.element, forSegmentAt: element.offset)
}
segmentedControl.selectedSegmentIndex = state.selectedIndex
}
usage:
// store `selectorLabel` data
saveState(of: selectorLabel)
// restore `selectorLabel` data
loadState(on: selectorLabel)
Note that it is not a good idea to store data like this to userdefaults at all. If you want to access some data from anywhere in code, you should follow singleton pattern and define your own singleton instance instead of standard userdefault.
Just store the value as a string, instead of an integer index.
UserDefaults.standard.set(selectorLabel.titleForSegment(at: selectorLabel.selectedSegmentIndex), forKey: "stateSelected")
And then to retrieve:
UserDefaults.standard.string(forKey: "stateSelected")
EDIT: #rmaddy is correct above - you should ideally be storing an index value like you're already doing, and then using an array to determine which title the index refers to (cleaner than just using a title as a reference). You could make this array global so you can access from anywhere, if you must.
segmentedControlTitles: [String] = ["LBs & INs", "KGs & CMs"]
And then call by
let index = UserDefaults.standard.integer(forKey: "stateSelected")
let title = segmentedControlTitles[index]

Is it possible to customise the section index list in a UITableView (such as font)?

UITableView gives you the ability to edit colors of the section index list with properties such as
var sectionIndexColor: UIColor? { get set }
var sectionIndexBackgroundColor: UIColor? { get set }
Is it possible to edit it in other ways?
Looking for Swift implementations.
It is possible to adjust it if you're okay with accessing private properties.
I believe this would pass store approval but don't take my word for it.
Here are the properties/functions you would be able to access. https://github.com/nst/iOS-Runtime-Headers/blob/master/Frameworks/UIKit.framework/UITableViewIndex.h
I've tested changing the font with the following and it worked.
func viewDidLoad() {
super.viewDidLoad()
DispatchQueue.main.async { [unowned self] in
if let tableViewIndex = self.tableView.subviews.first(where: { String(describing: type(of: $0)) == "UITableViewIndex" }) {
tableViewIndex.setValue(*Insert Font Here*, forKey: "font")
self.tableView.reloadSectionIndexTitles()
}
}
}

Update Core Data from a UISwitch inside a TableViewCell

I have a static table that is bound to some Core Data values, I'm not sure how I would use NSFetchedResultsController in this instance, though I have seen discussions about how much more recommended it is.
I grab my Core Data object which is passed via Segue.
I also have a model that is setup to contain questions, with one of the properties containing the Core Data value (this is why I don't think I can use NSFetchedResultsController, as even though my Core Data entity contains some of the values I need, I'm not sure I would need a full data set)
self.surveyQuestion.append(SurveyQuestion(question: "Does the customer have a 'Proof of ownership'?", answer: coreDataEntity.isProofOfOwnership as Bool))
The questions are Survey related such as "Is your property X?" with a UiSwitch which is mapped to a Core Data value:
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
// Configure the cell...
let cell : SurveyQuestionTableViewCell = tableView.dequeueReusableCellWithIdentifier("SurveyQuestionCell") as! SurveyQuestionTableViewCell
cell.lblQuestion.textColor = UIColor.grayColor()
let surveyQuestion = self.surveyQuestion[indexPath.row]
cell.lblQuestion.text = surveyQuestion.question
cell.toggQuestion.on = surveyQuestion.answer
if cell.toggQuestion.on {
cell.lblQuestion.textColor = UIColor.blackColor()
cell.accessoryType = .DetailDisclosureButton
}
return cell
}
Now, when I tap on the UISwitch I need it to update the Core Data value, and reload the table, its hooked up to a CustomTableViewCell like so:
*edit - Nearly got this thing working! heres my UITableViewCell class
class SurveyQuestionTableViewCell: UITableViewCell {
let managedObjectContext = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
#IBOutlet weak var lblQuestion: UILabel!
#IBOutlet weak var toggQuestion: UISwitch!
var surveyQuestionReference : SurveyQuestion?
var tableViewReference : UITableView?
#IBAction func toggledQuestion(sender: AnyObject) {
let tempContext: NSManagedObjectContext = NSManagedObjectContext(concurrencyType: .PrivateQueueConcurrencyType)
tempContext.parentContext = self.managedObjectContext
tempContext.performBlock({
let entityName = "CoreDataEntity"
let request = NSFetchRequest(entityName: entityName)
request.predicate = NSPredicate(format: "id = %#", self.surveyQuestionReference!.id)
do {
let results = try tempContext.executeFetchRequest(request) as? [NSManagedObject]
if results!.count > 0{
if let moc = self.managedObjectContext{
moc.performBlockAndWait({
for result in results!{
result.setValue(self.toggQuestion.on, forKey: (self.surveyQuestionReference?.property)!)
}
})
}
}
do {
try tempContext.save()
//completion(finished: true)
} catch let error {
print(error)
}
}catch{
print("error")
}
})
print(sender)
dispatch_async(dispatch_get_main_queue()) {
self.tableViewReference!.reloadData()
}
}
I can obviously access the bit where the toggle is triggered, but this class doesn't know anything about the Core Data bit, I was thinking about using notifications but that just seems kind of messy...
when you create your cell, pass in a reference to the coredata object, and the tableView itself and store them as attributes of SurveyQuestionTableViewCell, then you can do everything you need to in setSelected()
in your custom cell class, add an attribute for the question
class SurveyQuestionTableViewCell: UITableViewCell {
#IBOutlet weak var lblQuestion: UILabel!
#IBOutlet weak var toggQuestion: UISwitch!
var surveyQuestionReference : SurveyQuestionType
vat tableViewReference : UITableView
...
and then in cellForRowAtIndexPath after you create the cell
cell.surveyQuestionReference = surveyQuestion
cell.tableViewReference = tableView
where SurveyQuestionType is whatever you have previously defined
in setSelected, you can use those stored attributes
surveyQuestionReference = self.toggQuestion.on
tableViewReference.reloadData()
Here's another option, using a shared Instance
import Foundation
import MapKit
import CoreData
class DataModelInstance : NSObject, NSCoding
{
var appDelegate : AppDelegate?
var managedContext : NSManagedObjectContext?
var persistentStoreCoordinator : NSPersistentStoreCoordinator?
// plus whatever else you need
class var sharedInstance : DataModelInstance
{
struct Singleton
{
static let instance = DataModelInstance()
}
return Singleton.instance
}
and then in any class which needs access to this data model
var dataModel = DataModelInstance.sharedInstance
I know there are those who just won't ever use singletons, but it can be a much more elegant solution to making these attributes available where they are needed
With a shared data model, you can simply move all of your data attributes out of the class they are currently in, and reference them through the data model - then if you have the same data model in your custom cell class, you can do whatever you can do in the main view. To keep your GUI and processing logic separate, you can put everything in the data model
dataModel.refreshTable()
and then define a function in the data model that takes care of your table view - you could save all current edits to the data, and reload, without having to put any of that logic in individual cell classes
for updating any record in core data try to use this code:
let managedObjectContext:NSManagedObjectContext=(UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext!
let req=NSFetchRequest(entityName: "Entity Name")
req.returnsObjectsAsFaults=false
let result:NSArray=try! managedObjectContext.executeFetchRequest(req)
if result.count>0{
let res=result[Int(indexPath.row!]as! NSManagedObject
res.setValue("The Value", forKey: "Key Name")
do {
try managedObjectContext.save()
} catch _ { print("Update Unsuccessful") }
You must use [unowned self] in within the closure. See Apple's docs. This is how it's done. See also CoreDataKit, a 28-star github repo Core Data stack. It's available on cocoapods and honestly, why not just drop something like this into your app and not worry about "unowned selves" and other philosophical brain twisters, eh?
if let moc = self.managedObjectContext{
moc.performBlockAndWait({
/* In here we are in a closure (Swift version of a block), so "self" is problematic. Use unowned self instead (in objective c you'd have to do weak self). */
[unowned self] in
for result in results!{
result.setValue(self.toggQuestion.on,
forKey: (self.surveyQuestionReference?.property)!)
}
})
}

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