I have a ForEach which takes a Binding<[String]> and it compiled with Xcode11 beta5 fine but with beta6 it says Type of expression is ambiguous without more context on the Text("...") inside the ForEach and I can't find the mistake. Is it that I can't iterate over such a binding anymore?
struct ForEachItem1: View {
#Binding var items: [String]
var body: some View {
ForEach($items) { item in
Text("Hello world") // Type of expression is ambiguous without more context
}
}
}
struct ForEachItem2: View {
#Binding var items: [String]
var body: some View {
ForEach($items) { (item: Binding<String>) in
Text("Hello world") // Type of expression is ambiguous without more context
}
}
}
The conditional conformance of Binding to Collection was removed (see Xcode11 Beta5 Release Notes for deprecation notice). It can't be found in later release notes/releases.
Related
Hello I am running into a problem here and I do not have a consistent behavior between my .sheet() view when running on ios13 or ios14
I got a view like this :
#State private var label: String = ""
#State private var sheetDisplayed = false
///Some code
var body: some View {
VStack {
Button(action: {
self.label = "A label"
self.isDisplayed = true
}) {
Text("test")
}
}.sheet(isPresented: $sheetDisplayed, onDismiss: {
self.label = ""
}) {
Text(self.label)
}
}
On ios 13 this work as expected btn click -> set label -> call sheet -> display "A label" in a Text view.
On ios14 I got an empty string in self.label when in sheet closure, hence it does not display anything.
Did I missed something ? Is it an iOS 14 bug or did I had it wrong on ios13 and that got corrected.
PS: I have a couple of other variables that are passed in the closure I simplified it.
Your code have expectation of view update/creation order, but in general it is undefined (and probably changed in iOS 14).
There is explicit way to pass information inside sheet - use different sheet creator, ie. .sheet(item:...
Here is working reliable example. Tested with Xcode 12 / iOS 14
struct ContentView: View {
#State private var item: Item?
struct Item: Identifiable {
let id = UUID()
var label: String = ""
}
var body: some View {
VStack {
Button(action: {
self.item = Item(label: "A label")
}) {
Text("test")
}
}.sheet(item: $item, onDismiss: {
self.item = nil
}) {
Text($0.label)
}
}
}
This is some really strange behaviour in iOS 14, which doesn't appear to be documented.
Using the other answer here and the comment on this thread, I used #Binding to solve the issue as it seemed the cleanest and most SwiftUI-esq solution.
I have no idea why this behaviour has changed, and it seems less intuitive than before, so I'm assuming its a bug!
An example:
struct MainView: View {
#State private var message = ""
#State private var showSheet = false
var body: some View {
Button(action: {
self.message = "This will display the correct message"
self.showSheet = true
}, label: {
Text("Test Button")
})
.sheet(isPresented: self.$showSheet) {
SheetView(message: self.$message)
}
}
}
struct SheetView: View {
#Binding var message: Int
var body: some View {
Text(self.message)
}
}
The behaviour changed with SwiftUI 2.0, so it affects MacOS 11 as well, just adding a binding to the view fixes it even when that binding is never used, which makes me think this is an implementation bug.
Additionally just using the details state variable in a Text() within the body of the view also fixes it.
struct MyViewController : View {
#State var details: String?
#State var showDetails = false
// #Binding var havingAbindingFixesIt: String?
var body: some View {
VStack {
// Text(details ?? "")
Text("Tap here for details")
.onTapGesture {
self.details = "These are the details"
self.showDetails.toggle()
}
.sheet(isPresented: $showDetails) { Text(details ?? "") }
}
}
}
I have following code in SwiftUI
struct AuthorView: View {
let authors = ["a","b","c"]
#State private var selectedAuthor = ""
var body: some View {
VStack {
Text("Authors").font(.title)
HStack {
List(authors, id: \.self, selection: $selectedAuthor) {author in
Text(author).tag(author)
}
Spacer()
}
}
}
but I can't compile due to error "Generic parameter 'SelectionValue' could not be inferred". What I'm doing wrong here? My aim is to get selected author for later use.
Thanks.
List selection by interface contract should be optional, so here is fixed part
struct AuthorView: View {
let authors = ["a","b","c"]
#State private var selectedAuthor: String? // << !!
// ... other code
}
Hello I am running into a problem here and I do not have a consistent behavior between my .sheet() view when running on ios13 or ios14
I got a view like this :
#State private var label: String = ""
#State private var sheetDisplayed = false
///Some code
var body: some View {
VStack {
Button(action: {
self.label = "A label"
self.isDisplayed = true
}) {
Text("test")
}
}.sheet(isPresented: $sheetDisplayed, onDismiss: {
self.label = ""
}) {
Text(self.label)
}
}
On ios 13 this work as expected btn click -> set label -> call sheet -> display "A label" in a Text view.
On ios14 I got an empty string in self.label when in sheet closure, hence it does not display anything.
Did I missed something ? Is it an iOS 14 bug or did I had it wrong on ios13 and that got corrected.
PS: I have a couple of other variables that are passed in the closure I simplified it.
Your code have expectation of view update/creation order, but in general it is undefined (and probably changed in iOS 14).
There is explicit way to pass information inside sheet - use different sheet creator, ie. .sheet(item:...
Here is working reliable example. Tested with Xcode 12 / iOS 14
struct ContentView: View {
#State private var item: Item?
struct Item: Identifiable {
let id = UUID()
var label: String = ""
}
var body: some View {
VStack {
Button(action: {
self.item = Item(label: "A label")
}) {
Text("test")
}
}.sheet(item: $item, onDismiss: {
self.item = nil
}) {
Text($0.label)
}
}
}
This is some really strange behaviour in iOS 14, which doesn't appear to be documented.
Using the other answer here and the comment on this thread, I used #Binding to solve the issue as it seemed the cleanest and most SwiftUI-esq solution.
I have no idea why this behaviour has changed, and it seems less intuitive than before, so I'm assuming its a bug!
An example:
struct MainView: View {
#State private var message = ""
#State private var showSheet = false
var body: some View {
Button(action: {
self.message = "This will display the correct message"
self.showSheet = true
}, label: {
Text("Test Button")
})
.sheet(isPresented: self.$showSheet) {
SheetView(message: self.$message)
}
}
}
struct SheetView: View {
#Binding var message: Int
var body: some View {
Text(self.message)
}
}
The behaviour changed with SwiftUI 2.0, so it affects MacOS 11 as well, just adding a binding to the view fixes it even when that binding is never used, which makes me think this is an implementation bug.
Additionally just using the details state variable in a Text() within the body of the view also fixes it.
struct MyViewController : View {
#State var details: String?
#State var showDetails = false
// #Binding var havingAbindingFixesIt: String?
var body: some View {
VStack {
// Text(details ?? "")
Text("Tap here for details")
.onTapGesture {
self.details = "These are the details"
self.showDetails.toggle()
}
.sheet(isPresented: $showDetails) { Text(details ?? "") }
}
}
}
I have been using SwiftUI for a few months now an I am having difficulty with using ForEach.
I am aware that the ForEach protocol demands a unique identifier, but I have used /.self to overcome that aspect of the protocol.
Now unit testing a ForEach statement but I am getting a warning which is preventing build.
Warning is Result of 'ForEach' initializer is
unused
import SwiftUI
struct GetdOrderView: View {
#State private var myFamily = ["Ufuoma","Efe","David","Vicky","Beth"]
//The use of ForEach
func myForachOne() {
ForEach((0 ... myFamily.count), id: \.self) {member in
VStack {
Text("\(member)")
}
}
}
var body: some View {
Text("Hello world")
}
}
Instead of
func myForachOne() {
Use
func myForachOne() -> some View {
//Use This
import SwiftUI
struct GetdOrderView: View {
#State private var myFamily = ["Ufuoma","Efe","David","Vicky","Beth"]
//The use of ForEach
func myForachOne() -> some View {
ForEach((0 ... myFamily.count), id: \.self) {member in
VStack {
Text("\(member)")
}
}
}
var body: some View {
Text("Hello world")
}
}
I'm having a problem trying to get textfields working in SwiftUI.
I get Fatal error: Accessing State> outside View.body whenever I try to run the following code.
Anyone have a suggestion?
struct SearchRoot : View {
#State var text: String = ""
var body: some View {
HStack {
TextField($text,
placeholder: Text("type something here..."))
Button(action: {
// Closure will be called once user taps your button
print(self.$text)
}) {
Text("SEND")
}
}
}
}
I'm running Xcode Version 11.0 beta (11M336w) on macOS 10.15 Beta (19A471t)
Edit: Simplified code, still getting the same error.
struct SearchRoot : View {
#State var text: String = ""
var body: some View {
TextField($text,
placeholder: Text("type something here..."))
}
}
The compiler emits an error if the $ operator is used outside body, in a View.
The button initializer is defined as:
init(action: #escaping () -> Void, #ViewBuilder label: () -> Label)
You're using $ in an escaping closure, in the first snippet of code.
That means the action may outlive (escape) the body, hence the error.
The second snippet compiles and works fine for me.
Eureka! SwiftUI wants a single source of truth.
What I neglected to include in my original code snippets is that this struct is within a tabbed application.
To fix this I needed to define the #State var text: String = "" in the struct that creates the top level TabbedView, then use $Binding in the SearchRoot.
I'm not sure if this is works as designed or just a beta 1 issue, but it's the way it works for now.
struct ContentView : View {
#State private var selection = 0
#State private var text: String = "searching ex"
var body: some View {
TabbedView(selection: $selection){
ShoppingListRoot().body.tabItemLabel(Text("Cart")).tag(0)
SearchRoot(text: $text).body.tabItemLabel(Text("Search")).tag(1)
StoreRoot().body.tabItemLabel(Text("Store")).tag(2)
BudgetRoot().body
.tabItemLabel(Text("Budget"))
.tag(3)
SettingsRoot().body
.tabItemLabel(Text("Settings"))
.tag(4)
}
}
}