I am trying to reload the data every .onAppear, but if I change the #AppStorage nearMeter's value in the SettingsView, it isn't updating the value in the reloadNearStops func and using the previous #AppStorage value.
struct SettingsView: View {
#AppStorage(“nearMeter”) var nearMeter: Int = 1
#State var meters = ["100 m","200 m","400 m","500 m","750 m","1 km"]
var body: some View {
………
Picker(selection: $nearMeter, label: HStack {
Text(NSLocalizedString(“near_stops_distance”, comment: ""))
}) {
ForEach(0 ..< meters.count, id: \.self) {
Text(meters[$0])
}
}}}
struct FavouritesView: View {
#AppStorage(“nearMeter”) var nearMeter: Int = 1
func reloadNearStops(nearMeter: Int) {
print(nearMeter)
readNearStopsTimeTable.fetchTimeTable(nearMeter: getLonLatSpan(nearMeter: nearMeter), lat: (locationManager.lastLocation?.coordinate.latitude)!, lon: (locationManager.lastLocation?.coordinate.longitude)!)
}
func getLonLatSpan(nearMeter: Int) -> Double {
let meters = [100,200,400,500,750,1000]
if nearMeter < meters.count {
return Double(meters[nearMeter]) * 0.00001
}
else {
return 0.001
}
}
var body: some View {
.....
……….
.onAppear() {
if locationManager.lastLocation?.coordinate.longitude != nil {
if hasInternetConnection {
reloadNearStops(nearMeter: nearMeter)
}
}
}}
AppStorage won't call a function but onChange can call a function when AppStorage has changed.
struct StorageFunctionView: View {
#AppStorage("nearMeter") var nearMeter: Int = 1
#State var text: String = ""
var body: some View {
VStack{
Text(text)
Button("change-storage", action: {
nearMeter = Int.random(in: 0...100)
})
}
//This will listed for changes in AppStorage
.onChange(of: nearMeter, perform: { newNearMeter in
//Then call the function and if you need to pass the new value do it like this
fetchSomething(value: newNearMeter)
})
}
func fetchSomething(value: Int) {
text = "I'm fetching \(value)"
}
}
Related
Every time I press the button an instance of the School struct is created. I want to show that change on the screen but the button doesn't update. What am I missing to make it work?
import SwiftUI
struct School {
static var studentCount = 0
static func add(student: String) {
print("\(student) joined the school.")
studentCount += 1
}
}
struct ReviewClosuresAndStructs: View {
#State private var test = School.studentCount
var body: some View {
VStack {
Button(action: {
School.add(student: "Tyler")
}, label: {
Text("Press me. \n Students: \(test)")
})
}
}
}
struct ReviewClosuresAndStructs_Preview: PreviewProvider {
static var previews: some View {
ReviewClosuresAndStructs()
}
}
struct School {
var studentCount = 0 // <= here
mutating func add(student: String) { // <= here
print("\(student) joined the school.")
studentCount += 1
}
}
struct ReviewClosuresAndStructs: View {
#State private var test = School() // <= here
var body: some View {
VStack {
Button(action: {
test.add(student: "Tyler")
}, label: {
Text("Press me. \n Students: \(test.studentCount)") // <= here
})
}
}
}
The following picker isn't updating $selection. Regardless of what the Picker shows while running the app, selection.rawValue always returns 0.
What is preventing the Picker from updating the State variable selection?
import SwiftUI
struct OrderPicker: View {
let initialIndex: Int
#State private var selection: Index
enum Index: Int, CaseIterable, Identifiable {
case none = 0,
first = 1,
second = 2,
third = 3
var id: Self { self }
}
init(initialIndex: Int) {
self.initialIndex = initialIndex
_selection = State(initialValue: OrderPicker.Index(rawValue: initialIndex) ?? .none)
}
var body: some View {
Form {
Picker("Order in list", selection: $selection) {
ForEach(Index.allCases) { index in
Text(String(describing: index)).tag(index)
}
}
}
.frame(height: 116)
}
func getOrderIndex() -> Int {
let index = selection.rawValue
return index
}
}
Here is an approach for you:
struct ContentView: View {
#State private var selection: PickerType = PickerType.none
var body: some View {
OrderPicker(selection: $selection)
}
}
struct OrderPicker: View {
#Binding var selection: PickerType
var body: some View {
Form {
Picker("Order in list", selection: $selection) {
ForEach(PickerType.allCases, id: \.self) { item in
Text(item.rawValue)
}
}
.pickerStyle(WheelPickerStyle())
.onChange(of: selection, perform: { newValue in
print(newValue.rawValue, newValue.intValue)
})
}
}
}
enum PickerType: String, CaseIterable {
case none, first, second, third
var intValue: Int {
switch self {
case .none: return 0
case .first: return 1
case .second: return 2
case .third: return 3
}
}
}
import Foundation
class Card: Identifiable, ObservableObject {
var id = UUID()
var result: String = ""
init() {
for _ in 1...10 {
let suit = ["D","K","B","S"][Int(arc4random() % 4]
let numStr = ["1","2","3","4"][Int(arc4random() % 4]
result = suit + numStr
}
}
}
import SwiftUI
struct EasyModeView: View {
#ObservedObject var cardModel: Card
var body : some View {
HStack {
ForEach((1...10, id: \.self) { _ in
Button { } label: { Image(cardModel.result) } } }
}
}
I created loop but it always shows me 10 same cards and i want all 10 different.
My Images in Assets are named same as combination of two variables example "D1","D2","S1","S2" etc.
Here is a right way of what you are trying:
struct ContentView: View {
var body: some View {
EasyModeView()
}
}
struct EasyModeView: View {
#StateObject var cardModel: Card = Card()
var body : some View {
HStack {
ForEach(cardModel.results) { card in
Button(action: {}, label: {
Text(card.result)
.padding(3.0)
.background(Color.yellow.cornerRadius(3.0))
})
}
}
Button("re-set") { cardModel.reset() }.padding()
}
}
struct CardType: Identifiable {
let id: UUID = UUID()
var result: String
}
class Card: ObservableObject {
#Published var results: [CardType] = [CardType]()
private let suit: [String] = ["D","K","B","S"]
init() { initializing() }
private func initializing() {
if (results.count > 0) { results.removeAll() }
for _ in 0...9 { results.append(CardType(result: suit.randomElement()! + String(describing: Int.random(in: 1...4)))) }
}
func reset() { initializing() }
}
Result:
You are using only one card, instead of creating 10. Fix like this
struct EasyModeView: View {
var body : some View {
HStack {
ForEach(0..<10) { _ in
Button { } label: {
Image(Card().result)
}
}
}
}
}
In the following example how can I change the value of activeSheet based on how SwiftUI updates aArrived and bArrived?
struct ContentView: View {
#AppStorage("didAArrive") var aArrived: Bool = false
#AppStorage("didBArrive") var bArrived: Bool = false
enum ActiveSheet: Identifiable {
case aArrived, bArrived
var id: Int {
hashValue
}
}
#State private var activeSheet: ActiveSheet?
var body: some View {
Text("Hello")
.sheet(
item: $activeSheet,
content: { item in
switch item {
case .aArrived:
Text("A arrived")
case .bArrived:
Text("B arrived")
}
}
)
}
}
You can create a custom binding for the sheet which gets its value based on aArrived and bArrived. The binding value will be initialised based on aArrived or bArrived and get updated every time that either one changes.
struct ContentView: View {
#AppStorage("didAArrive") var aArrived: Bool = false
#AppStorage("didBArrive") var bArrived: Bool = false
enum ActiveSheet: Identifiable {
case aArrived, bArrived
var id: Int {
hashValue
}
}
var body: some View {
let sheetBinding = Binding<ActiveSheet?>(
get: {
if aArrived && bArrived {
return ActiveSheet.aArrived
} else if aArrived {
return ActiveSheet.aArrived
} else if bArrived {
return ActiveSheet.bArrived
} else {
return nil
}
},
set: { _ in }
)
VStack(spacing: 20) {
Toggle("A arrived", isOn: $aArrived)
Toggle("B arrived", isOn: $bArrived)
}
.sheet(
item: sheetBinding,
content: { item in
switch item {
case .aArrived:
Text("A arrived")
case .bArrived:
Text("B arrived")
}
}
)
}
}
I am currently having trouble modifying a String value using a TextField. Here is my (simplified) code so far:
class GradeItem: ObservableObject {
#Published var name: String
#Published var scoredPoints: Double
#Published var totalPoints: Double
let isUserCreated: Bool
init(name: String, scoredPoints: Double, totalPoints: Double, isUserCreated: Bool) {
self.name = name
self.scoredPoints = scoredPoints
self.totalPoints = totalPoints
self.isUserCreated = isUserCreated
}
}
var courses: [Course] {
// initialization code...
}
struct GradeCalculatorView: View {
#State var selectedCourseIndex: Int = 0
var body: some View {
VStack {
// allows user to select a course:
ForEach(0 ..< courses.count) { i in
Button(action: {
self.selectedCourseIndex = i
}, label: {
Text(courses[i].name)
})
}
CourseView(course: courses[selectedCourseIndex])
}
}
}
struct CourseView: View {
#ObservedObject var course: Course // passed in from GradeCalculatorView
var body: some View {
VStack(alignment: .leading) {
Text(course.name)
ForEach(course.categories, id: \.name) { category in
GradeCategoryView(category: category)
}
}.padding(.leading).frame(alignment: .leading)
}
}
struct GradeCategoryView: View {
#ObservedObject var category: GradeCategory // passed in from CourseView
var body: some View {
VStack(alignment: HorizontalAlignment.leading) {
HStack {
Text(category.name)
Spacer()
}
ForEach(category.items, id:\.name) { item in
GradeItemRow(item: item)
}
}
}
}
struct GradeItemRow: View {
#ObservedObject var item: GradeItem // passed in from GradeCategoryView
var body: some View {
TextField("Item Name", text: $item.name)
}
}
I cannot seem to modify the GradeItem object's name using the TextField. When the TextField is edited, its text changes temporarily. However, when the GradeItemRow View is reloaded, it displays the GradeItem object's original name, rather than its updated name.
Would somebody please be able to help?
Thanks in advance
UPDATE: As per your requests, I have added more context to this sample code.
I know that this does not work, as when I attempt to modify a GradeItem's name with a TextField, it changes temporarily. However, when I select a different course and then the course I was initially on, the TextField displays the unmodified name value.
The following test works.
class GradeItem: ObservableObject {
#Published var name: String
#Published var scoredPoints: Double
#Published var totalPoints: Double
let isUserCreated: Bool
init(name: String, scoredPoints: Double, totalPoints: Double, isUserCreated: Bool) {
self.name = name
self.scoredPoints = scoredPoints
self.totalPoints = totalPoints
self.isUserCreated = isUserCreated
}
init() {
self.name = "gradeItem" + UUID().uuidString
self.scoredPoints = 0.0
self.totalPoints = 0.0
self.isUserCreated = false
}
}
class Course: ObservableObject {
#Published var name: String
#Published var categories: [GradeCategory]
init(name: String, categories: [GradeCategory]) {
self.name = name
self.categories = categories
}
init() {
self.name = "course_" + UUID().uuidString
self.categories = [GradeCategory]()
self.categories.append(GradeCategory())
}
}
class GradeCategory: ObservableObject {
#Published var name: String
#Published var items: [GradeItem]
init(name: String, items: [GradeItem]) {
self.name = name
self.items = items
}
init() {
self.name = "category_" + UUID().uuidString
self.items = [GradeItem]()
self.items.append(GradeItem())
}
}
struct GradeItemRow: View {
#ObservedObject var item: GradeItem // passed in from GradeCategoryView
var body: some View {
TextField("Item Name", text: $item.name).textFieldStyle(RoundedBorderTextFieldStyle())
}
}
struct GradeCategoryView: View {
#ObservedObject var category: GradeCategory // passed in from CourseView
var body: some View {
VStack(alignment: .leading) {
HStack {
Text(category.name)
Spacer()
}
ForEach(category.items, id: \.name) { item in
GradeItemRow(item: item)
}
}
}
}
struct CourseView: View {
#Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
#ObservedObject var course: Course // passed in from ContentView
var body: some View {
VStack(alignment: .leading) {
Button(action: {
self.presentationMode.wrappedValue.dismiss()
}, label: {
Text("done")
})
Spacer()
Text(course.name)
ForEach(course.categories, id: \.name) { category in
GradeCategoryView(category: category)
}
Spacer()
}.padding(.leading).frame(alignment: .leading)
}
}
struct ContentView: View {
#State var courses: [Course] = [Course(), Course()]
#State var selectedCourseIndex: Int = 0
#State var showCourse = false
var body: some View {
VStack {
ForEach(0 ..< courses.count) { i in
Button(action: {
self.selectedCourseIndex = i
self.showCourse = true
}, label: {
Text(self.courses[i].name)
})
}
}.sheet(isPresented: self.$showCourse) {
CourseView(course: self.courses[self.selectedCourseIndex])
}
}
}