I'm trying to modify the fonts of a SwiftUI Picker. I believe I have tried adding modifiers to
all of the Picker initializer formats and none of them seem to have any effect. The only modification
I have found to work at all is the visible text when I wrap the Picker in a menu.
Here's some test code:
struct PickerFontView: View {
#State private var years: [String] = ["2010", "2011", "2012", "2013", "2014", "2015", "2016", "2017", "2018", "2019" ]
#State private var selectedYear: String = "2015"
var body: some View {
VStack {
Text("You chose:")
Text("\(selectedYear)")
//none of these font modifiers work in any initializer
Picker("Choose a Year", selection: $selectedYear) {
ForEach(years, id: \.self) {
Text($0).font(.title)
}.font(.title)
}.font(.title)
.padding(.bottom)
//only wrapping in Menu can I change font for display
Menu {
Picker("Choose a Year", selection: $selectedYear) {
ForEach(years, id: \.self) { y in
Text(y)
}
}//picker
} label: { Text(selectedYear).font(.title)} //this
}
.font(.system(size: 50))//does not affect the non-menu picker
}
}
This is the view:
This is what I would like to modify:
Any guidance would be appreciated. Xcode 14.2 iOS 16.2
Related
I get this error every time I launch a secondary picker.
The first picker works okay.
However when I switch pickers & scroll, I get the following:
Here is my entire code (written as a test of this problem):
import SwiftUI
struct ContentView: View {
#State private var selectedItem = 0
#State private var isMainPickerHidden = false
#State private var isSecondaryPickerHidden = true
var colors = ["Red", "Green", "Blue", "Tartan"]
var sizes = ["Tiny", "Small", "Medium", "Large", "Super Size"]
var body: some View {
ZStack {
Color.yellow.edgesIgnoringSafeArea(.all)
ZStack {
VStack {
Picker(selection: $selectedItem, label: Text("Please choose a color")) {
ForEach(colors.indices, id: \.self) {
Text(self.colors[$0])
}
}.hiddenConditionally(isHidden: isMainPickerHidden)
Text("You selected: \(colors[selectedItem])")
.hiddenConditionally(isHidden: isMainPickerHidden)
}
VStack {
Picker(selection: $selectedItem, label: Text("Please choose a size")) {
ForEach(sizes.indices, id: \.self) {
Text(self.sizes[$0])
}
}.hiddenConditionally(isHidden: isSecondaryPickerHidden)
Text("You selected: \(sizes[selectedItem])")
.hiddenConditionally(isHidden: isSecondaryPickerHidden)
Spacer()
Button(action: {
isSecondaryPickerHidden = !isSecondaryPickerHidden
isMainPickerHidden = !isMainPickerHidden
}) {
Text("Switch Pickers")
}.padding()
}
}
}
}
}
// =========================================================================================================
extension View {
func hiddenConditionally(isHidden: Bool) -> some View {
isHidden ? AnyView(hidden()) : AnyView(self)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
What is the correct syntax for the ForEach{} to avoid this problem?
This is because you use the same selectedItem for both pickers.
If in the second picker you select the last item (index 4) and then you switch to the first picker (max index = 3), then in this line:
Text("You selected: \(colors[selectedItem])")
you'll try accessing the index which is out of range.
To fix this you can use a separate #State variable for each picker:
struct ContentView: View {
#State private var selectedColorIndex = 0
#State private var selectedSizeIndex = 0
Picker(selection: $selectedColorIndex, label: Text("Please choose a color")) {
Picker(selection: $selectedSizeIndex, label: Text("Please choose a size")) {
I want to basically make didSelectRow like UITableView in SwiftUI.
This is the code:
struct ContentView: View {
var testData = [Foo(name: "1"),
Foo(name: "2"),
Foo(name: "3"),
Foo(name: "4"),
Foo(name: "5")]
#State var selected: Foo?
var body: some View {
NavigationView {
VStack {
List(testData, id: \.name, selection: $selected) { foo in
HStack {
Text(foo.name)
}
}.navigationBarTitle("Selected \(selected?.name ?? "")")
Button("Check:") {
print(selected?.name)
}
}
}
}
I was thought if I click the cell then selected should contains the selected value, but it's not. The selected has no value. And the cell not clickable.
So I added a Button.
NavigationView {
VStack {
List(testData, id: \.name, selection: $selected) { foo in
HStack {
Text(foo.name)
Button("Test") {
print("\(foo) is selected.")
print(selected?.name)
}
}
}.navigationBarTitle("Selected \(selected?.name ?? "")")
Button("Check:") {
print(selected?.name)
}
}
Now, click works, but actually foo is the one I want there's no need selected why selection of the List is here.
Not sure anything I missed. Should the Button is necessary for the List "didSelectRow"? thanks!
EDIT
After a bit more investigation, my current conclusion is:
For single selections, no need call List(.. selection:). But you have to use Button or OnTapGesture for clickable.
List(.. selection:) is only for edit mode, which is multiple selection, as you can see the selection: needs a set. My example should be
#State var selected: Set<Foo>?
On iOS selection works in Edit mode by design
/// Creates a list with the given content that supports selecting multiple
/// rows.
///
>> /// On iOS and tvOS, you must explicitly put the list into edit mode for
>> /// the selection to apply.
///
/// - Parameters:
/// - selection: A binding to a set that identifies selected rows.
/// - content: The content of the list.
#available(watchOS, unavailable)
public init(selection: Binding<Set<SelectionValue>>?, #ViewBuilder content: () -> Content)
so you need either add EditButton somewhere, or activate edit mode programmatically, like
List(selection: $selection) {
// ... other code
}
.environment(\.editMode, .constant(.active)) // eg. persistent edit mode
Update: Here is some demo of default SwiftUI List selection
struct DemoView: View {
#State private var selection: Set<Int>?
#State private var numbers = [0,1,2,3,4,5,6,7,8,9]
var body: some View {
List(selection: $selection) {
ForEach(numbers, id: \.self) { number in
VStack {
Text("\(number)")
}
}.onDelete(perform: {_ in})
}
.environment(\.editMode, .constant(.active))
}
}
This is my model
struct ListItemModel: Codable, Identifiable {
let id: String
let name: String
}
This is the view that will be displayed with a Picker. The list will be populated by an outside source but I simplified it for this example.
struct TypeSelectionView: View {
#State private var selected = 0
let testList = [ListItemModel(id: "11", name: "name1"),
ListItemModel(id: "12", name: "name2")]
var body: some View {
VStack {
Picker(selection: $selected, label: Text("Pick a Type")) {
ForEach(0 ..< testList.count) {
Text(testList[$0].name)
}
}.labelsHidden()
Picker(selection: $selected, label: Text("Pick a Type")) {
ForEach(testList) {type in
Text(type.name)
}
}.labelsHidden()
Text("Selected Type: \(testList[selected].name)")
Spacer()
}
}
}
struct TypeSelectionView_Previews: PreviewProvider {
static var previews: some View {
TypeSelectionView()
}
}
The first Picker is correctly changing the display of the Text view on the page when the Picker changes but the second Picker does not. Is their a way to make the second Picker do the do the same thing where as you change the Picker the Text view will update accordingly
or is the first Picker the way you should always go when making Pickers in SwiftUI?
The reason your second Picker doesn't work is that the values returned by the Picker correspond to the id of the items. In the case of your second Picker, those are String.
You can apply a .tag() to each item, and then the Picker will return that. For example, if you added an explicit tag it would work:
Text(type.name).tag(testList.firstIndex(where: { $0.id == type.id })!)
Alternatively, if you changed your id values to be Int and the id values corresponded to the position in the array, it would work.
Because of the difficulties of implementing a tag, it is easy to see why many developers choose to just iterate on 0 ..< testList.count.
Ok so this my first ever answer for a stack overflow question, I'm quite a newbie myself but hopefully I can be of some help.
The code when placed in to Xcode shows two pickers whose initial values are name1 but when you change the first picker the second picker and the text displaying the selected type change accordingly, but because both pickers share the same source of truth #State private var selected = 0, changing this will have unintended side effects.
import SwiftUI
struct TypeSelectionView: View {
#State private var selected = 0
#State var testList = [ListItemModel(id: "11", name: "name1"),
ListItemModel(id: "12", name: "name2")]
#State var priorityTypes = ["low", "medium", "high", "critical"]
var body: some View {
VStack {
Picker("Pick a Type", selection: $selected) {
ForEach(0..<testList.count) {
Text(self.testList[$0].name)
}
}.labelsHidden()
Picker("Pick a Type", selection: $selected) {
ForEach(0..<testList.count) {
Text(self.testList[$0].name)
}
}.labelsHidden()
Text("Selected Type: \(testList[selected].name)")
Spacer()
}
}
}
struct TypeSelectionView_Previews: PreviewProvider {
static var previews: some View {
TypeSelectionView()
}
}
struct ListItemModel: Codable, Identifiable {
let id: String
let name: String
}
I want a list with rows, with each row having 2 Textfields inside of it. Those rows should be saved in an array, so that I can use the data in an other view for further functions. If the text in the Textfield is changed, the text should be saved inside the right entry in the array.
You also can add new rows to the list via a button, which should also change the array for the rows.
The goal is to have a list of key value pairs, each one editable and those entries getting saved with the current text.
Could someone help me and/or give me hint for fixing this problem?
So far I have tried something like this:
// the array of list entries
#State var list: [KeyValue] = [KeyValue()]
// the List inside of a VStack
List(list) { entry in
KeyValueRow(list.$key, list.$value)
}
// the single item
struct KeyValue: Identifiable {
var id = UUID()
#State var key = ""
#State var value = ""
}
// one row in the list with view elements
struct KeyValueRow: View {
var keyBinding: Binding<String>
var valueBinding: Binding<String>
init(_ keyBinding: Binding<String>, _ valueBinding: Binding<String>){
self.keyBinding = keyBinding
self.valueBinding = valueBinding
}
var body: some View {
HStack() {
TextField("key", text: keyBinding)
Spacer()
TextField("value", text: valueBinding)
Spacer()
}
}
}
Also, about the button for adding new entries.
Problem is that if I do the following, my list in the view goes blank and everything is empty again
(maybe related: SwiftUI TextField inside ListView goes blank after filtering list items ?)
Button("Add", action: {
self.list.append(KeyValue())
})
I am not sure what the best practice is keep a view up to date with state in an array like this, but here is one approach to make it work.
For the models, I added a list class that conforms to Observable object, and each KeyValue item alerts it on changes:
class KeyValueList: ObservableObject {
#Published var items = [KeyValue]()
func update() {
self.objectWillChange.send()
}
func addItem() {
self.items.append(KeyValue(parent: self))
}
}
class KeyValue: Identifiable {
init(parent: KeyValueList) {
self.parent = parent
}
let id = UUID()
private let parent: KeyValueList
var key = "" {
didSet { self.parent.update() }
}
var value = "" {
didSet { self.parent.update() }
}
}
Then I was able to simply the row view to just keep a single piece of state:
struct KeyValueRow: View {
#State var item: KeyValue
var body: some View {
HStack() {
TextField("key", text: $item.key)
Spacer()
TextField("value", text: $item.value)
Spacer()
}
}
}
And for the list view:
struct TextFieldList: View {
#ObservedObject var list = KeyValueList()
var body: some View {
VStack {
List(list.items) { item in
HStack {
KeyValueRow(item: item)
Text(item.key)
}
}
Button("Add", action: {
self.list.addItem()
})
}
}
}
I just threw an extra Text in there for testing to see it update live.
I did not run into the Add button blanking the view as you described. Does this solve that issue for you as well?
Working code example for iOS 15
In SwiftUI, Apple recommends passing the binding directly into the List constructor and using a #Binding in the ViewBuilder block to iterate through with each element.
Apple recommends this approach over using the Indices to iterate over the collection since this doesn't reload the whole list every time a TextField value changes (better efficiency).
The new syntax is also back-deployable to previous releases of SwiftUI apps.
struct ContentView: View {
#State var directions: [Direction] = [
Direction(symbol: "car", color: .mint, text: "Drive to SFO"),
Direction(symbol: "airplane", color: .blue, text: "Fly to SJC"),
Direction(symbol: "tram", color: .purple, text: "Ride to Cupertino"),
Direction(symbol: "bicycle", color: .orange, text: "Bike to Apple Park"),
Direction(symbol: "figure.walk", color: .green, text: "Walk to pond"),
Direction(symbol: "lifepreserver", color: .blue, text: "Swim to the center"),
Direction(symbol: "drop", color: .indigo, text: "Dive to secret airlock"),
Direction(symbol: "tram.tunnel.fill", color: .brown, text: "Ride through underground tunnels"),
Direction(symbol: "key", color: .red, text: "Enter door code:"),
]
var body: some View {
NavigationView {
List($directions) { $direction in
Label {
TextField("Instructions", text: $direction.text)
}
}
.listStyle(.sidebar)
.navigationTitle("Secret Hideout")
}
}
}
struct Direction: Identifiable {
var id = UUID()
var symbol: String
var color: Color
var text: String
}
No need to mess up with classes, Observable, Identifiable. You can do it all with structs.
Note, that version below will do fine for insertions, but fail if you try to delete array elements:
import SwiftUI
// the single item
struct KeyValue {
var key: String
var value: String
}
struct ContentView: View {
#State var boolArr: [KeyValue] = [KeyValue(key: "key1", value: "Value1"), KeyValue(key: "key2", value: "Value2"), KeyValue(key: "key3", value: "Value3"), KeyValue(key: "key4", value: "Value4")]
var body: some View {
NavigationView {
// id: \.self is obligatory if you need to insert
List(boolArr.indices, id: \.self) { idx in
HStack() {
TextField("key", text: self.$boolArr[idx].key)
Spacer()
TextField("value", text: self.$boolArr[idx].value)
Spacer()
}
}
.navigationBarItems(leading:
Button(action: {
self.boolArr.append(KeyValue(key: "key\(UInt.random(in: 0...100))", value: "value\(UInt.random(in: 0...100))"))
print(self.boolArr)
})
{ Text("Add") }
, trailing:
Button(action: {
self.boolArr.removeLast() // causes "Index out of range" error
print(self.boolArr)
})
{ Text("Remove") })
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Update:
A little trick to make it work with deletions as well.
import SwiftUI
// the single item
struct KeyValue {
var key: String
var value: String
}
struct KeyValueView: View {
#Binding var model: KeyValue
var body: some View {
HStack() {
TextField("Key", text: $model.key)
Spacer()
TextField("Value", text: $model.value)
Spacer()
}
}
}
struct ContentView: View {
#State var kvArr: [KeyValue] = [KeyValue(key: "key1", value: "Value1"), KeyValue(key: "key2", value: "Value2"), KeyValue(key: "key3", value: "Value3"), KeyValue(key: "key4", value: "Value4")]
var body: some View {
NavigationView {
List(kvArr.indices, id: \.self) { i in
KeyValueView(model: Binding(
get: {
return self.kvArr[i]
},
set: { (newValue) in
self.kvArr[i] = newValue
}))
}
.navigationBarItems(leading:
Button(action: {
self.kvArr.append(KeyValue(key: "key\(UInt.random(in: 0...100))", value: "value\(UInt.random(in: 0...100))"))
print(self.kvArr)
})
{ Text("Add") }
, trailing:
Button(action: {
self.kvArr.removeLast() // Works like a charm
print(self.kvArr)
})
{ Text("Remove") })
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Swift 5.5
This version of swift enables one line code for this by passing the bindable item directly from the array.
struct DirectionsList: View {
#Binding var directions: [Direction]
var body: some View {
List($directions) { $direction in
Label {
TextField("Instructions", text: $direction.text)
} icon: {
DirectionsIcon(direction)
}
}
}
}
I can't find how to add some element in a picker view in SwiftUI, in my sample, I want add "Z" value in picker when I click the button.
struct ContentView: View {
#State var values: [String] = ["A", "B", "C"]
#State private var selectedValue = 0
var body: some View {
NavigationView {
Form {
Section {
Picker(selection: $selectedValue, label: Text("Value")) {
ForEach(0 ..< values.count) {
Text(self.values[$0])
}
}
}
Button(action: {
self.values.append("Z")
}, label: {
Text("Add")
})
}.navigationBarTitle("Select a value")
}
}
When I click on the button, Z is added to "values" array but Picker is not refreshed.
Thank you :)
You must identify values by id for SwiftUI to make it's changes detectable:
ForEach(0 ..< self.values.count, id: \.self) {
Text(self.values[$0])
}
This way SwiftIU knowns it should rebuild the picker on change.
Tip: You can use elements directly like this:
ForEach(values, id: \.self) {
Text($0)
}
Don't forget to change the selectedValue type and value to match with the dataSource IF you followed the tip above:
#State private var selectedValue = "A"
Change selectedValue from int to String
#State private var selectedValue = "A"
add the parameter id and the tag modifier
Picker(selection: $selectedValue, label: Text("Value")) {
ForEach(values, id: \.self) {
Text($0).tag(String($0))
}
}