Currently, I am using #State for an Array of SKProducts
#State var products = [SKProduct]()
var body: some View {
ScrollView(.horizontal){
LazyHStack {
if products.count > 0 {
ForEach(products.indices) { index in
let product = self.products[index]
// ProductCell(product: product)
}
ForEach(1...products.count, id: \.self) { count in
let product = $products[count]
// ProductCell(product: Binding.constant(products[count]))
// ProductCell(name: <#Binding<String>#>).padding()
}
}
}
}.onAppear(perform: {
Purchases.shared.offerings { (offerings, error) in
if let tempPackages = offerings?.current?.availablePackages {
for package in tempPackages {
products.append(package.product)
}
}
}
})
}
I am trying to pass off an individual product to another view below:
ForEach(1...products.count, id: \.self) { count in
let product = $products[count]
}
However "product" is considered an "error type"
I am new to SwiftUI and I cannot for the life of me figure out what I am doing wrong. Thank you for your time and consideration.
products is an array, $products is a binding.
products[0] is the first element of an array. $products[0] means nothing because a binding doesn't have a subscript accessor.
Remove the $.
Related
I'm getting a weird memory leak in SwiftUI when using List and id: \.self, where only some of the items are destroyed. I'm using macOS Monterey Beta 5.
Here is how to reproduce:
Create a new blank SwiftUI macOS project
Paste the following code:
class Model: ObservableObject {
#Published var objs = (1..<100).map { TestObj(text: "\($0)")}
}
class TestObj: Hashable {
let text: String
static var numDestroyed = 0
init(text: String) {
self.text = text
}
static func == (lhs: TestObj, rhs: TestObj) -> Bool {
return lhs.text == rhs.text
}
func hash(into hasher: inout Hasher) {
hasher.combine(text)
}
deinit {
TestObj.numDestroyed += 1
print("Deinit: \(TestObj.numDestroyed)")
}
}
struct ContentView: View {
#StateObject var model = Model()
var body: some View {
NavigationView {
List(model.objs, id: \.self) { obj in
Text(obj.text)
}
Button(action: {
var i = 1
model.objs.removeAll(where: { _ in
i += 1
return i % 2 == 0
})
}) {
Text("Remove half")
}
}
}
}
Run the app, and press the "Remove half" button. Keep pressing it until all the items are gone. However, if you look at the console, you'll see that only 85 items have been destroyed, while there were 99 items. The Xcode memory graph also supports this.
This seems to be caused by the id: \.self line. Removing it and switching it out for id: \.text fixes the problem.
However the reason I use id: \.self is because I want to support multiple selection, and I want the selection to be of type Set<TestObj>, instead of Set<UUID>.
Is there any way to solve this issue?
If you didn't have to use selection in your List, you could use any unique & constant id, for example:
class TestObj: Hashable, Identifiable {
let id = UUID()
/* ... */
}
And then your List with the implicit id: \.id:
List(model.objs) { obj in
Text(obj.text)
}
This works great. It works because now you are no longer identifying the rows in the list by a reference type, which is kept by SwiftUI. Instead you are using a value type, so there aren't any strong references causing TestObjs to not deallocate.
But you need selection in List, so see more below about how to achieve that.
To get this working with selection, I will be using OrderedDictionary from Swift Collections. This is so the list rows can still be identified with id like above, but we can quickly access them. It's partially a dictionary, and partially an array, so it's O(1) time to access an element by a key.
Firstly, here is an extension to create this dictionary from the array, so we can identify it by its id:
extension OrderedDictionary {
/// Create an ordered dictionary from the given sequence, with the key of each pair specified by the key-path.
/// - Parameters:
/// - values: Every element to create the dictionary with.
/// - keyPath: Key-path for key.
init<Values: Sequence>(_ values: Values, key keyPath: KeyPath<Value, Key>) where Values.Element == Value {
self.init()
for value in values {
self[value[keyPath: keyPath]] = value
}
}
}
Change your Model object to this:
class Model: ObservableObject {
#Published var objs: OrderedDictionary<UUID, TestObj>
init() {
let values = (1..<100).map { TestObj(text: "\($0)")}
objs = OrderedDictionary<UUID, TestObj>(values, key: \.id)
}
}
And rather than model.objs you'll use model.objs.values, but that's it!
See full demo code below to test the selection:
struct ContentView: View {
#StateObject private var model = Model()
#State private var selection: Set<UUID> = []
var body: some View {
NavigationView {
VStack {
List(model.objs.values, selection: $selection) { obj in
Text(obj.text)
}
Button(action: {
var i = 1
model.objs.removeAll(where: { _ in
i += 1
return i % 2 == 0
})
}) {
Text("Remove half")
}
}
.onChange(of: selection) { newSelection in
let texts = newSelection.compactMap { selection in
model.objs[selection]?.text
}
print(texts)
}
.toolbar {
ToolbarItem(placement: .primaryAction) {
EditButton()
}
}
}
}
}
Result:
Using SwiftUI, CoreData and #FetchRequest wrapper, I simply do not get any view updates on cahnegs on related entities. I set up the following simple and working example:
The CoreData model looks as follows:
GroupEntity -hasMany[items]-> ItemEntity
ItemEntity -hasOne[group]-> GroupEntity
I added two extensions to the CoreData autogenerated Classes to get around the nasty optionals here. The button at the bottom creates a group with three items in it. They're named equally but are truely different due to their unique id. The view simply lists a group and all its related items and their according value below. Tapping an item increases it's value by one. Tapping the "change GroupName" button at the bottom of each group section changes the group's name. There is no additional code than the following:
import SwiftUI
extension ItemEntity {
var wName: String { name ?? "nameless item"}
}
extension GroupEntity {
var wName: String { name ?? "nameless group" }
var aItems: [ItemEntity] {
let set = items as? Set<ItemEntity> ?? []
return set.sorted {
$0.wName < $1.wName
}
}
}
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(entity: GroupEntity.entity(), sortDescriptors: []) var groups: FetchedResults<GroupEntity>
var body: some View {
List {
ForEach(groups, id: \.self) { group in
Section(header: Text("\(group.wName) >> \(group.aItems.reduce(0, {$0 + $1.value}))")) {
ForEach(group.aItems, id: \.id) { (item: ItemEntity) in
Text("\(item.wName) >> \(item.value)")
.onTapGesture {
item.value = item.value + 1
print("item value: \(item.value)")
// -> value changed & stored, but view IS NOT UPDATED
try? moc.save()
}
}
Button(action: {
group.name = group.wName + " [changed]"
// -> value changed,stored and view IS UPDATED
try? moc.save()
}) {
Text("change \(group.wName)")
}
}
}
Button(action: addGroupItems) {
Text("Add Group with Items")
}
}
}
func addGroupItems() {
let group = GroupEntity(context: moc)
group.id = UUID()
group.name = "G1"
let item1 = ItemEntity(context: moc)
item1.id = UUID()
item1.name = "I1"
item1.value = 1
group.addToItems(item1)
let item2 = ItemEntity(context: moc)
item2.id = UUID()
item2.name = "I2"
item2.value = 2
group.addToItems(item2)
let item3 = ItemEntity(context: moc)
item3.id = UUID()
item3.name = "I3"
item3.value = 3
group.addToItems(item3)
// save
try? moc.save()
}
}
Whenever the Group's name is changed, the View automatically refreshes and makes the change visible. But when tapping an item, it's value increases (as the print statement proves) but the view is not updated. Please note the additional requirement, that the group's section header also includes a computed sum of all it's item's values. This schould also be updated when an item changes. That's why simply exporting the Item into an separated itemRowView(item: item) and declaring item as #ObservedObject var item: ItemEntity in there is not the solution here.
I assume, that the #FetchRequest wrapper somehow ignores all changes to related items. But I cannot belief that it's that useless for related data because that's CoreDatas main power?
Thank you all for any helpful comment and idea!
Just by idea - try the following
.onTapGesture {
item.value = item.value + 1
print("item value: \(item.value)")
// -> value changed & stored, but view IS NOT UPDATED
try? moc.save()
group.objectWillChange.send() // << here !!
}
Okay so I found a solution that worked for me. Adding a publisher watching for changes in the managedObjectContext and updating whenever a change isd etected does the trick.
struct ContentView: View {
private var mocDidChanged = NotificationCenter.default.publisher(for: .NSManagedObjectContextObjectsDidChange)
/* ... */
var body: some View {
List { /* .. */ }.onReceive(self.mocDidChanged) { _ in
self.refresh()
}
}
func refresh() {
/* update related state variables here */
}
}
I want to display multiple text fields, representing scores of each part of a match.
Example : For a volleyball match, we have 25/20, 25/22, 25/23. The global score is 3/0.
The global components architecture :
>> ParentComponent
>> MainComponent
>> X TextFieldsComponent (2 text fields, home/visitor score)
The lowest component, TextFieldsComponent, contains basic bindings :
struct TextFieldsComponent: View {
#ObservedObject var model: Model
class Model: ObservableObject, Identifiable, CustomStringConvertible {
let id: String
#Published var firstScore: String
#Published var secondScore: String
var description: String {
"\(firstScore) \(secondScore)"
}
init(id: String, firstScore: String = .empty, secondScore: String = .empty) {
self.id = id
self.firstScore = firstScore
self.secondScore = secondScore
}
}
var body: some View {
HStack {
TextField("Dom.", text: $model.firstScore)
.keyboardType(.numberPad)
TextField("Ext.", text: $model.secondScore)
.keyboardType(.numberPad)
}
}
}
The parent component needs to show the total score of all parts of the match. And I wanted to try a Combine binding/stream to get the total score.
I tried multiple solutions and I ended up with this non-working code (the reduce seems to not be take all the elements of the array but internally stores a previous result) :
struct MainComponent: View {
#ObservedObject var model: Model
#ObservedObject private var totalScoreModel: TotalScoreModel
class Model: ObservableObject {
#Published var scores: [TextFieldsComponent.Model]
init(scores: [TextFieldsComponent.Model] = [TextFieldsComponent.Model(id: "main")]) {
self.scores = scores
}
}
private final class TotalScoreModel: ObservableObject {
#Published var totalScore: String = ""
private var cancellable: AnyCancellable?
init(publisher: AnyPublisher<String, Never>) {
cancellable = publisher.print().sink {
self.totalScore = $0
}
}
}
init(model: Model) {
self.model = model
totalScoreModel = TotalScoreModel(
publisher: Publishers.MergeMany(
model.scores.map {
Publishers.CombineLatest($0.$firstScore, $0.$secondScore)
.map { ($0.0, $0.1) }
.eraseToAnyPublisher()
}
)
.reduce((0, 0), { previous, next in
guard let first = Int(next.0), let second = Int(next.1) else { return previous }
return (
previous.0 + (first == second ? 0 : (first > second ? 1 : 0)),
previous.1 + (first == second ? 0 : (first > second ? 0 : 1))
)
})
.map { "[\($0.0)] - [\($0.1)]" }
.eraseToAnyPublisher()
)
}
var body: some View {
VStack {
Text(totalScoreModel.totalScore)
ForEach(model.scores) { score in
TextFieldsComponent(model: score)
}
}
}
}
I'm searching for a solution to get an event on each binding change, and merge it in a single stream, to display it in MainComponent.
N/B: The TextFieldsComponent needs to be usable in standalone too.
MergeMany is the correct approach here, as you started out yourself, though I think you overcomplicated things.
If you want to display the total score in the View (and let's say the total score is "owned" by Model instead of TotalScoreModel, which makes sense since it owns the underlying scores), you'd then need to signal that this model will change when any of the underlying scores will change.
Then you can provide the total score as a computed property, and SwiftUI will read the updated value when it recreates the view.
class Model: ObservableObject {
#Published var scores: [TextFieldsComponent.Model]
var totalScore: (Int, Int) {
scores.map { ($0.firstScore, $0.secondScore) }
.reduce((0,0)) { $1.0 > $1.1 ? ( $0.0 + 1, $0.1 ) : ($0.0, $0.1 + 1) }
}
private var cancellables = Set<AnyCancellable>()
init(scores: [TextFieldsComponent.Model] = [.init(id: "main")]) {
self.scores = scores
// get the ObservableObjectPublisher publishers
let observables = scores.map { $0.objectWillChange }
// notify that this object will change when any of the scores change
Publishers.MergeMany(observables)
.sink(receiveValue: self.objectWillChange.send)
.store(in: &cancellables)
}
}
Then, in the View, you can just use the Model.totalScore as usual:
#ObservedObject var model: Model
var body: some View {
Text(model.totalScore)
}
using core data im storing some airport and for every airport i'm storing different note
I have created the entity Airport and the entity Briefing
Airport have 1 attribute called icaoAPT and Briefing have 4 attribute category, descript, icaoAPT, noteID
On my detailsView I show the list all the noted related to that airport, I managed to have a dynamic fetch via another view called FilterList
import SwiftUI
import CoreData
struct FilterLIst: View {
var fetchRequest: FetchRequest<Briefing>
#Environment(\.managedObjectContext) var dbContext
init(filter: String) {
fetchRequest = FetchRequest<Briefing>(entity: Briefing.entity(), sortDescriptors: [], predicate: NSPredicate(format: "airportRel.icaoAPT == %#", filter))
}
func update(_ result : FetchedResults<Briefing>) ->[[Briefing]]{
return Dictionary(grouping: result) { (sequence : Briefing) in
sequence.category
}.values.map{$0}
}
var body: some View {
List{
ForEach(update(self.fetchRequest.wrappedValue), id: \.self) { (section : Briefing) in
Section(header: Text(section.category!)) {
ForEach(section, id: \.self) { note in
Text("hello")
/// Xcode error Cannot convert value of type 'Text' to closure result type '_'
}
}
}
}
}
}
on this view I'm try to display all the section divided by category using the func update...
but Xcode give me this error , I can't understand why..Cannot convert value of type 'Text' to closure result type '_'
fore reference I list below my detailsView
import SwiftUI
struct DeatailsView: View {
#Environment(\.managedObjectContext) var dbContext
#Environment(\.presentationMode) var presentation
#State var airport : Airport
#State var note = ""
#State var noteTitle = ["SAFTY NOTE", "TAXI NOTE", "CPNOTE"]
#State var notaTitleSelected : Int = 0
#State var notaID = ""
var body: some View {
Form{
Section(header: Text("ADD NOTE Section")) {
TextField("notaID", text: self.$notaID)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
TextField("add Note descrip", text: self.$note)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
Picker(selection: $notaTitleSelected, label: Text("Class of Note")) {
ForEach(0 ..< noteTitle.count) {
Text(self.noteTitle[$0])
}
}
HStack{
Spacer()
Button(action: {
let nota = Briefing(context: self.dbContext)
nota.airportRel = self.airport
nota.icaoAPT = self.airport.icaoAPT
nota.descript = self.note
nota.category = self.noteTitle[self.notaTitleSelected]
nota.noteID = self.notaID
do {
try self.dbContext.save()
debugPrint("salvato notazione")
} catch {
print("errore nel salva")
}
}) {
Text("Salva NOTA")
}
Spacer()
}
}
Section(header: Text("View Note")) {
FilterLIst(filter: airport.icaoAPT ?? "NA")
}
}
}
}
thanks for the help
This is because you try to iterate over a single Briefing object and a ForEach loop expects a collection:
List {
ForEach(update(self.fetchRequest.wrappedValue), id: \.self) { (section: Briefing) in
Section(header: Text(section.category!)) {
ForEach(section, id: \.self) { note in // <- section is a single object
Text("hello")
/// Xcode error Cannot convert value of type 'Text' to closure result type '_'
}
}
}
}
I'd recommend you to extract the second ForEach to another method for clarity. This way you can also be sure you're passing the argument of right type ([Briefing]):
func categoryView(section: [Briefing]) -> some View {
ForEach(section, id: \.self) { briefing in
Text("hello")
}
}
Note that the result of your update method is of type [[Briefing]], which means the parameter in the ForEach is section: [Briefing] (and not Briefing):
var body: some View {
let data: [[Briefing]] = update(self.fetchRequest.wrappedValue)
return List {
ForEach(data, id: \.self) { (section: [Briefing]) in
Section(header: Text("")) { // <- can't be `section.category!`
self.categoryView(section: section)
}
}
}
}
This also means you can't write section.category! in the header as the section is an array.
You may need to access a Briefing object to get a category:
Text(section[0].category!)
(if you're sure the first element exists).
For clarity I specified types explicitly. It's also a good way to be sure you always use the right type.
let data: [[Briefing]] = update(self.fetchRequest.wrappedValue)
However, Swift can infer types automatically. In the example below, the data will be of type [[Briefing]]:
let data = update(self.fetchRequest.wrappedValue)
I want to implement a swipe-to-delete functionality on a SwiftUI Section by using the .onDelete modifier. The problem is that it always deletes the first item in the list.
My view has a list with dynamic sections created with a ForEach.
struct SetListView : View {
var setlist: Setlist
var body : some View {
List {
ForEach(setlist.sets) {
SetSection(number: $0.id, songs: $0.songs)
}
}
.listStyle(.grouped)
}
}
In each section, there is another ForEach to create the dynamic rows:
private struct SetSection : View {
var number: Int
#State var songs: [Song]
var body : some View {
Section (header: Text("Set \(number)"), footer: Spacer()) {
ForEach(songs) { song in
SongRow(song: song)
}
.onDelete { index in
self.songs.remove(at: index.first!)
}
}
}
}
While debugging, I found out that the IndexSet is referring to the current section instead of the row. So when deleting items from the first section, always the first item gets deleted (as the index for the first section is 0).
Is this a bug in SwiftUI?
If not, then how could I get the index for the row?
In simple terms, a solution to this problem is to pass the section to your deletion method by:
Adopting RandomAccessCollection on your source data.
Binding the section in your outer ForEach and then using it in your inner ForEach, passing it to your deletion method:
List {
ForEach(someGroups.indices) { section in
bind(self.someGroups[section]) { someGroup in
Section(header: Text(someGroup.displayName)) {
ForEach(someGroup.numbers) { number in
Text("\(number)")
}
.onDelete { self.delete(at: $0, in: section) }
}
}
}
}
func delete(at offsets: IndexSet, in section: Int) {
print("\(section), \(offsets.first!)")
}
A complete, contrived working example
(Also available in Gist form for convenience):
import SwiftUI
func bind<Value, Answer>(_ value: Value, to answer: (Value) -> Answer) -> Answer { answer(value) }
struct Example: View {
struct SomeGroup: Identifiable, RandomAccessCollection {
typealias Indices = CountableRange<Int>
public typealias Index = Int;
var id: Int
var displayName: String
var numbers: [Int]
public var endIndex: Index {
return numbers.count - 1
}
public var startIndex: Index {
return 0
}
public subscript(position: Int) -> Int {
get { return numbers[position] }
set { numbers[position] = newValue }
}
}
var someGroups: [SomeGroup] = {
return [
SomeGroup(id: 0, displayName: "First", numbers: [1, 2, 3, 4]),
SomeGroup(id: 1, displayName: "Second", numbers: [1, 3, 5, 7])
]
}()
var body: some View {
List {
ForEach(someGroups.indices) { section in
bind(self.someGroups[section]) { someGroup in
Section(header: Text(someGroup.displayName)) {
ForEach(someGroup.numbers) { number in
Text("\(number)")
}
.onDelete { self.delete(at: $0, in: section) }
}
}
}
}
.listStyle(.grouped)
}
func delete(at offsets: IndexSet, in section: Int) {
print("\(section), \(offsets.first!)")
}
}
Many thanks to #rob-mayoff who pointed me in the right direction for this solution via Twitter!
I had exactly the same problem. Turns out, SwiftUI's (current?) implementation does not recognize nested lists. This means that each SetSection in your List is interpreted as a single row even though you have a ForEach in it with the actual SongRows. Hence, it the IndexSet (index.first!) always returns zero.
What I've also noticed is that even with a flat hierarchy such as..
List {
Section {
ForEach(...) {
...
}
}
Section {
ForEach(...) {
...
}
}
}
..individual rows cannot be moved between sections. This is also true when directly using two ForEach, i.e. without the Section wrappers.
We should probably file a report for each phenomenon.
It seems to work fine on Xcode 12.5
I'm using it like this:
struct Sections: View {
var items: [SomeData]
private var sections: [Date: [SomeData]] {
Dictionary(grouping: items, by: { $0.date })
}
private var headers: [Date] {
sections.map({ $0.key }).sorted().reversed()
}
var body: some View {
List {
ForEach(headers, id: \.self) { date in
Section(header: Text(date.friendly) {
AList(items: sections[date]!)
}
}
}
}
}
struct AList: View {
var items: [SomeData]
var body: some View {
ForEach(items) { data in
...
}
.onDelete(perform: delete)
}
private func delete(at offsets: IndexSet) {
// You can use `items.remove(atOffsets: offsets)`
for offset in offsets {
let data = items[offset]
print("\(data)")
// You can check here that this is the item that you want to remove and then you need to remove it from your data source.
// I'm using Realm and #Published vars that works fine, you should adapt to your logic.
}
}
}