i'm writing a todo list app, and i'm having trouble initializing the detail view.
in HomeView i use a foreach to set up each line.
struct HomeListView: View {
ForEach(items) { item in
NavigationLink(destination: ItemDetailView(item: item, editMode: true)) {
ItemView(title: item.title, text: item.text, type: item.type, dueDate: item.dueDate)
}
}
in the ItemDetailView i defined a init() to set up title, text and other properties.
struct ItemDetailView: View {
#State var title: String = ""
#State var text: String = ""
#State var type: Int = 0
#State var dueDate: Date = Date()
init(item: ItemEntity, editMode: Bool) {
self.title = item.title
self.text = item.text
self.type = item.type
self.dueDate = item.dueDate
self.item = item
print(item.title)
if self.title.isEmpty {
print(self.title)
}
self.editMode = editMode
print(self.editMode)
}
}
when i run the app, in the console it prints
2
true
4
true
i can see that the init() receice the item and set editMode properly, but i can't figure out why the title, text, type and dueDate properties are set to their default values instead of the values in the item that the init receive.
does it have anything to do with the #State wrapper? how can i set their values to what i want?
Thanks for helping!
does it have anything to do with the #State wrapper?
Yes, it does. The state should be initialised via init in the next way (example for one)
struct ItemDetailView: View {
#State var title: String // << no, default value
...
init(item: ItemEntity, editMode: Bool) {
self._title = State<String>(initialValue: item.title) // << explicitly !!
...
Related
I'm trying to build an app (macOS, but would be the same for iOS) that creates a number of grids, the outcome of which is to be shown in a second screen. For this, I'm sharing data across these screens, and I'm running into an issue here, I hope someone can help or point me in the right direction. I'll share a simplified version of the code below (working in Xcode 14.0.1)
The code creates a dictionary that can be shown in a grid, on which calculations can be done. The idea is then to add this grid, with some descriptive variables, into another dictionary
The building blocks of the grid are cells
Import Foundation
struct Cell: Comparable, Equatable, Identifiable, Hashable {
static func == (lhs: Cell, rhs: Cell) -> Bool {
lhs.randomVarOne == rhs.randomVarOne
}
var randomVarOne: Double
var randomVarTwo: Bool
// other vars omitted here
var id: Int { randomVarOne }
static func < (lhs: Cell, rhs: Cell) -> Bool {
return lhs.randomVarOne < rhs.randomVarOne
}
}
this is also where there are a bunch of funcs to calculate next neighbor cells in the grid etc
then the grid is defined in a class:
class Info: ObservableObject, Hashable {
static func == (lhs: Info, rhs: Info) -> Bool {
lhs.grid == rhs.grid
}
func hash(into hasher: inout Hasher) {
hasher.combine(grid)
}
#Published var grid = [Cell]()
var arrayTotal = 900
#Published var toBeUsedForTheGridCalculations: Double = 0.0
var toBeUsedToSetTheVarAbove: Double = 0.0
var rowTotalDouble: Double {sqrt(Double(arrayTotal)) }
var rowTotal: Int {
Int(rowTotalDouble) != 0 ? Int(rowTotalDouble) : 10 }
The class includes a func to create and populate the grid with Cells and add these Cells to the grid var. It also includes the formulas to do the calculations on the grid using a user input. The class did not seem to need an initializer.
This is the Scenario struct:
struct Scenario: Comparable, Equatable, Identifiable, Hashable {
static func == (lhs: Scenario, rhs: Scenario) -> Bool {
lhs.scenarioNumber == rhs.scenarioNumber
}
func hash(into hasher: inout Hasher) {
hasher.combine(scenarioNumber)
}
var scenarioNumber: Int
var date: Date
var thisIsOneSnapshot = [Info]()
var id: Int { scenarioNumber }
static func < (lhs: Scenario, rhs: Scenario) -> Bool {
return lhs.scenarioNumber < rhs.scenarioNumber
}
}
added hashable since it uses the Info class as an input.
Then there is the class showing the output overview
class OutputOverview: ObservableObject {
#Published var snapshot = [Scenario]()
// the class includes a formula of how to add the collection of cells (grid) and the additional variables to the snapshot dictionary. Again no initializer was necessary.
Now to go to the ContentView.
struct ContentView: View {
#Environment(\.openURL) var openURL
var scenarioNumberInput: Int = 0
var timeStampAssigned: Date = Date.now
#ObservedObject private var currentGrid: Info = Info()
#ObservedObject private var scenarios: Combinations = Combinations()
var usedForTheCalculations: Double = 0.0
var rows =
[
GridItem(.flexible()),
// whole list of GridItems, I do not know how to calculate these:
// var rows = Array(repeating: GridItem(.flexible()), count: currentGrid.rowTotal)
//gives error "Cannot use instance member 'currentGrid' within property initializer;
// property iunitializers run before 'self' is available
]
var body: some View {
GeometryReader { geometry in
VStack {
ScrollView {
LazyHGrid(rows: rows, spacing: 0) {
ForEach(0..<currentGrid.grid.count, id :\.self) { w in
let temp = currentGrid.grid[w].varThatAffectsFontColor
let temp2 = currentGrid.grid[w].varThatAffectsBackground
Text("\(currentGrid.grid[w].randomVarOne, specifier: "%.2f")")
.frame(width: 25, height: 25)
.border(.black)
.font(.system(size: 7))
.foregroundColor(Color(wordName: temp))
.background(Color(wordName: temp2))
}
}
.padding(.top)
}
VStack{
HStack {
Button("Start") {
}
// then some buttons to do the calculations
Button("Add to collection"){
scenarios.addScenario(numbering: scenarioNumberInput, timeStamp:
Date.now, collection: currentGrid.grid)
} // this should add the newly recalculated grid to the dictionary
Button("Go to Results") {
guard let url = URL(string: "myapp://scenario") else { return }
openURL(url)
} // to go to the screen showing the scenarios
Then the second View, the ScenarioView:
struct ScenarioView: View {
#State var selectedScenario = 1
#ObservedObject private var scenarios: OutputOverview
var pickerNumbers = [ 1, 2, 3, 4 , 5]
// this is to be linked to the number of scenarios completed,this code is not done yet.
var rows =
[
GridItem(.flexible()),
GridItem(.flexible()),
// similar list of GridItems here....
var body: some View {
Form {
Section {
Picker("Select a scenario", selection: $selectedScenario) {
ForEach(pickerNumbers, id: \.self) {
Text("\($0)")
}
}
}
Section {
ScrollView {
if let idx = scenarios.snapshot.firstIndex(where:
{$0.scenarioNumber == selectedScenario}) {
LazyHGrid(rows: rows, spacing: 0) {
ForEach(0..<scenarios.snapshot[idx].thisIsOneSnapshot.count,
id :\.self) { w in
let temp =
scenarios.snapshot[idx].thisIsOneSnapshot[w].varThatAffectsFontColor
let temp2 =
scenarios.snapshot[idx].thisIsOneSnapshot[w].varThatAffectsBackground
Text("\(scenarios.snapshot[idx].thisIsOneSnapshot[w].randomVarOne, specifier: "%.2f")")
.frame(width: 25, height: 25)
.border(.black)
.font(.system(size: 7))
.foregroundColor(Color(wordName: temp))
.background(Color(wordName: temp2))
}
}
}
}
}
}
}
}
Now while the above does not (for the moment..) give me error messages, I am not able to run the PreviewProvider in the second View. The main problem is in #main:
import SwiftUI
#main
struct ThisIsTheNameOfMyApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
.handlesExternalEvents(matching: ["main"])
WindowGroup("Scenarios") {
ScenarioView()
// error messages here: 'ScenarioView' initializer is inaccessible due to "private"
// protection level - I don't know what is set to private in ScenarioView that could
// cause this
// second error message: missing argument for parameter 'scenarios' in call
}
.handlesExternalEvents(matching: ["scenario"])
}
}
I am at a loss on how to solve these 2 error messages and would be very grateful for any tips or guidance. Apologies if this question is very long, I scanned many other forum questions and could not find any good answers.
I have tried adding pro forma data in #main as follows
#main
struct FloodModelScenarioViewerApp: App {
#State var scenarios = Scenario(scenarioNumber: 1, date: Date.now)
var body: some Scene {
WindowGroup {
ContentView()
}
.handlesExternalEvents(matching: ["main"])
WindowGroup("Scenarios") {
ScenarioView(scenarios: scenarios)
}
.handlesExternalEvents(matching: ["scenario"])
}
}
This still gives 2 error messages:
same issue with regards to ScenarioView initialiser being inaccessible due to being 'private'
Cannot convert value of type 'Scenario' to expected argument type 'OutputOverview'
Just remove the private from
#ObservedObject private var scenarios: OutputOverview
The value is coming from he parent so the parent needs access. So put
#StateObject private var scenarios: OutputOverview = .init()
in FloodModelScenarioViewerApp
#StateObject is for initializing ObservableObjects and #ObservedObject is for passing them around.
I don't know if your code will work after you read this question, and that's because there are many things to correct, but you can start with these:
In Cell, you shouldn't use an id that is a variable, this may cause inconsistent behavior. Use something like:
let id = UUID()
When you initialize ContentView, you can't use currentGrid inside a variable because currentGrid will not be available before all variables are initialized. Meaning, you are trying to initialize rows before currentGrid actually exists. You can try using the .onAppear modifier:
var rows = [GridItem]()
var body: some View {
GeometryReader { geometry in
// ... view code in here
}
.onAppear {
var rows = Array(repeating: GridItem(.flexible()), count: currentGrid.rowTotal)
}
}
This creates the view and, before showing it, the grid is set to its proper value.
The message 'ScenarioView' initializer is inaccessible due to "private" protection level seems clear: you must provide a value to to the variable scenarios (it doesn't have a default value) but it's marked as private. Remove private.
#ObservedObject var scenarios: OutputOverview
Then, remember to pass a value of type OutputOverview for the variable when you call the view:
ScenarioView(scenarios: aVariableOfTypeOutputOverview)
The type mismatch error you get inside the #main code is also clear - you have defined a variable of type Scenario:
#State var scenarios = Scenario(scenarioNumber: 1, date: Date.now)
but ScenarioView requires another type:
#ObservedObject private var scenarios: OutputOverview
One of them needs change for your code to work.
I'm having a problem initialising my arrays in my view:
struct ProjectList: View
{
#ObservedObject var store: ProjectStore
#Binding var searchText: String
#State private var query: [Project] = []
#State private var indexes: [String] = ["E","F"]
init(store: ProjectStore, searchText: Binding<String>)
{
self.store = store
self._searchText = searchText
self.query = []
self.indexes = ["C","D"]
indexes = ["A","B"] //store.getIndexes(search: searchText.wrappedValue)
print (indexes)
}
}
indexes is being set to ["E","F"] not ["A","B"] in my init routine as I would have expected. What is happening?
Just don't init state when declare (because it is initialised only once and then works during view life-time, ie in body)
#State private var indexes: [String] // << only declare
init(store: ProjectStore, searchText: Binding<String>)
{
...
self._indexes = State(initialValue: ["C","D"]) // initialise !!
#State is property wrapper that means it takes the input of wrapped value and then modifies it, you should never set #State var in init, you have to set #State var directly if you really wanna initialize it in init you have to use init of #State since #State is a struct with syntactic sugar with #. Change
init(store: ProjectStore, searchText: Binding<String>)
{
self.store = store
self._searchText = searchText
self.query = []
self.indexes = ["C","D"]
indexes = ["A","B"] //store.getIndexes(search: searchText.wrappedValue)
print (indexes)
}
to :
init(store: ProjectStore, searchText: Binding<String>)
{
self.store = store
self._searchText = searchText
self.query = []
self.indexes = ["C","D"]
indexes = State(initialValue: ["C","D"]) //changed value
print (indexes)
}
Hey I am very new to tornadofx struggeling with async loading of data for the treeview. I am loading categories from a rest endpoint, which I want to show in there.
It seems like there's no direct data binding to the children.
when using 'bindChildren' I can provide the observable list, but I have to convert them into Node's. which then would make the populate block kind of obsolete.
What's the recommended way of doing this? I cannot find anything about this.
// Category
interface Category<T : Category<T>> {
val id: String
val name: String
val subcategories: List<T>?
}
//default category:
class DefaultCategory(override val name: String) : Category<DefaultCategory> {
override val id: String = "default"
override val subcategories: List<DefaultCategory>? = null
}
//ViewModel
class CategoryViewModel : ViewModel() {
val sourceProperty = SimpleListProperty<Category<*>>()
fun loadData() {
// load items for treeview into 'newItems'
sourceProperty.value = newItems
}
}
// TreeViewFactoryMethod
private fun createTreeView(
listProperty: SimpleListProperty<Category<*>>
): TreeView<Category<*>> {
return treeview {
root = TreeItem(DefaultCategory("Categories"))
isShowRoot = false
root.isExpanded = true
root.children.forEach { it.isExpanded = true }
cellFormat { text = it.name }
populate { parent ->
when (parent) {
root -> listProperty.value
else -> parent.value.subcategories
}
}
}
}
Assuming that on a button click I call viewmodel.loadData(), I would expect the TreeView to update as soon as there's some new data. (If I would've found a way to bind)
I've never had to use bindChildren for TornadoFX before and your use of async isn't very relevant to what I think is your primary problem. So, admittedly, this question kind of confused me at first but I'm guessing you're just wondering why the list isn't appearing in your TreeView? I've made a test example with changes to make it work.
// Category
interface Category<T : Category<T>> {
val id: String
val name: String
val subcategories: List<T>?
}
//default category:
class DefaultCategory(override val name: String) : Category<DefaultCategory> {
override val id: String = "default"
override val subcategories: List<DefaultCategory>? = null
}
//Just a dummy category
class ChildCategory(override val name: String) : Category<ChildCategory> {
override val id = name
override val subcategories: List<ChildCategory>? = null
}
//ViewModel
class CategoryViewModel : ViewModel() {
//filled with dummy data
val sourceProperty = SimpleListProperty<Category<*>>(listOf(
ChildCategory("Categorya"),
ChildCategory("Categoryb"),
ChildCategory("Categoryc"),
ChildCategory("Categoryd")
).asObservable())
fun loadData() {
sourceProperty.asyncItems {
//items grabbed somehow
listOf(
ChildCategory("Category1"),
ChildCategory("Category2"),
ChildCategory("Category3"),
ChildCategory("Category4")
).asObservable()
}
}
}
class TestView : View() {
val model: CategoryViewModel by inject()
override val root = vbox(10) {
button("Refresh Items").action {
model.loadData()
}
add(createTreeView(model.sourceProperty))
}
// TreeViewFactoryMethod
private fun createTreeView(
listProperty: SimpleListProperty<Category<*>>
): TreeView<Category<*>> {
return treeview {
root = TreeItem(DefaultCategory("Categories"))
isShowRoot = false
root.isExpanded = true
root.children.forEach { it.isExpanded = true }
cellFormat { text = it.name }
populate { parent ->
when (parent) {
root -> listProperty
else -> parent.value.subcategories
}
}
}
}
}
There are 2 important distinctions that are important.
1. The more relevant distinction is that inside the populate block, root -> listProperty is used instead of root.listProperty.value. This will make your list appear. The reason is that a SimpleListProperty is not a list, it holds a list. So, yes, passing in a plain list is perfectly valid (like how you passed in the value of the list property). But now that means the tree view isn't listening to your property, just the list you passed in. With that in mind, I would be considerate over the categories' subcategory lists are implemented as well.
2. Secondly, notice the use of asyncItems in the ViewModel. This will perform whatever task asynchronously, then set the items to list on success. You can even add fail or cancel blocks to it. I'd recommend using this, as long/intensive operations aren't supposed to be performed on the UI thread.
I'd like to have a function that takes an array with objects that could have id property on them. The function will remove the first object that has id and it matches function's second argument.
Here is my stub:
// #flow
function removeFromArrayByObjectId<T: {id?: string}>(array: Array<T>, id: any): Array<T> {
for (let i = 0; i < array.length; i++) {
if (array[i].id && array[i].id === id) {
array.splice(i, 1);
break;
}
}
return array;
}
export {
removeFromArrayByObjectId,
};
When I'm passing arr defined as (below) I'm getting
type Obj = { id: string, value: string };
const arr: Array<Obj> = [obj1, obj2];
Cannot call removeFromArrayByObjectId with array literal bound to array because string [1] is incompatible with undefined [2] in property id of array element.Flow(InferError)
However, when I remove ? from id? it works fine. I'm expecting that some arrays will have elements without the id so would like it to be optional. Any suggestions?
The error is very similar to the one mentioned in Why can't `{ a: string }` flow into `{ a?: string }`. Essentially, Flow does not know that removeFromArrayByObjectId does not manipulate the elements of array (e.g., delete a property). You'll want to mark T as "read-only" so Flow knows that the function will not do so.
function removeFromArrayByObjectId<T: $ReadOnly<{id?: string}>>(array: Array<T>, id: any): Array<T> {
for (let i = 0; i < array.length; i++) {
if (array[i].id && array[i].id === id) {
array.splice(i, 1);
break;
}
}
return array;
}
type Obj = { id: string, value: string };
declare var obj1: Obj;
declare var obj2: Obj;
const arr: Array<Obj> = [obj1, obj2];
const modified_arr: Array<Obj> = removeFromArrayByObjectId(arr);
Try Flow
Given this Model:
public class RSS2Feed {
public var channel: RSS2FeedChannel?
public init() {}
}
public class RSS2FeedChannel {
public var title: String?
public var description: String?
public init() {}
}
What would I need to do in order to get the property names and values of an RSS2FeedChannel instance?
Here's what I'm trying:
let feed = RSS2Feed()
feed.channel = RSS2FeedChannel()
feed.channel?.title = "The Channel Title"
let mirror = Mirror(reflecting: feed.channel)
mirror.children.first // ({Some "Some"}, {{Some "The Channel Title...
for (index, value) in mirror.children.enumerate() {
index // 0
value.label // "Some"
value.value // RSS2FeedChannel
}
Ultimately, I'm trying to create a Dictionary that matches the instance, using reflection, but so far I'm unable to get the properties name and values of the instance.
Documentation says that:
The optional label may be used when appropriate, e.g. to represent the name of a stored property or of an active enum case, and will be used for lookup when Strings are passed to the descendant method.
Yet I only get a "Some" string.
Also, the value property is returning a string with the Type RSS2FeedChannel when I would expect each children to be "An element of the reflected instance's structure."!
When i understand correct this should solve ur problem:
func aMethod() -> Void {
let feed = RSS2Feed()
feed.channel = RSS2FeedChannel()
feed.channel?.title = "The Channel Title"
// feed.channel?.description = "the description of your channel"
guard let channel = feed.channel else {
return
}
let mirror = Mirror(reflecting: channel)
for child in mirror.children {
guard let key = child.label else {
continue
}
let value = child.value
guard let result = self.unwrap(value) else {
continue
}
print("\(key): \(result)")
}
}
private func unwrap(subject: Any) -> Any? {
var value: Any?
let mirrored = Mirror(reflecting:subject)
if mirrored.displayStyle != .Optional {
value = subject
} else if let firstChild = mirrored.children.first {
value = firstChild.value
}
return value
}
just some little changes for swift 3:
private func unwrap(_ subject: Any) -> Any? {
var value: Any?
let mirrored = Mirror(reflecting:subject)
if mirrored.displayStyle != .optional {
value = subject
} else if let firstChild = mirrored.children.first {
value = firstChild.value
}
return value
}
You can use the descendent method on the Mirror object to get this information. It will return nil if the values aren't found or the optionals contain no value.
let mirror = Mirror(reflecting: feed.channel)
let child1 = mirror.descendant("Some", "title") // "The Channel Title"
// or on one line
let child3 = Mirror(reflecting: feed).descendant("channel", "Some", "title")