With AppKit I can do the following to bind multiple items to the same TextField, so when the TextField changes, they all update:
let options: [NSBindingOption : Any] = [NSBindingOption.validatesImmediately: true,
NSBindingOption.allowsEditingMultipleValuesSelection: true,
NSBindingOption.multipleValuesPlaceholder: "Multiple",
NSBindingOption.nullPlaceholder: "None",
NSBindingOption.conditionallySetsEditable: true]
textField.bind(.value, to: arrayController, withKeyPath: "selection.houseName", options: options)
In SwiftUI, I can bind a single item to a TextField like this:
TextField("My Text", text: $text)
However, that's just one item, I'm after the same behaviour as AppKit.
I could imagine one could write a custom binding, something like:
let propertyList = ["property1", "property2"]
let multipleValues = Binding<String>(
get: {
// return value if all items in propertyList are the same,
// else we need to return "Multiple", but not make "Multiple" editable text
},
set: { newValue in
for property in propertyList {
myObservable.setValue(newValue, forKeyPath: property)
}
}
)
TextField("My Text", text: multipleValues)
However, it seems I have to write the code to handle, null, multiple etc, which AppKit gives for free.
Is there a native SwiftUI system that has this behaviour?
Should I stick with AppKit for this? (Although, I'd like to move to SwiftUI)
Thank you for any advice here
Related
Let's say I have 2 entities:
GameSession :which has Attributes "date", "place", "numberofplayer" + a relationship called "players" with "Player"
Player: which has Attributes "name","score_part1","score_part2","score_part3" + a relationship with "GameSession"
the relationship is "one to many": One session can have many players
Let's say now I have a list of GameSession and when I click on on one (with a NavigationLink)
It sends me to a new view where I can see:
All the names of the players of that session (in text) and also right next to the player name I would like to have 3 TextField in which I can enter (an update) "score_part1","score_part2","score_part3" for every players of that session
Basically I am able to display the name of all the players of a given session, But it seems impossible to have the "score_part1","score_part2","score_part3" in editable TextField...
I have an error saying "Cannot convert value of type 'String' to expected argument type 'Binding<String>'"
Basically in my first view I have something like that:
struct RamiListePartieUIView: View {#Environment(.managedObjectContext) var moc#FetchRequest(entity: GameSession.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \GameSession.date, ascending: false)]) var gamesessions: FetchedResults<GameSession>
var body: some View {
VStack {
List {
ForEach(gamesessions, id: \.date) { session in
NavigationLink (destination: DetailPartieSelecUIView(session: session)){
Text("\(session.wrappedPlace) - le \(session.wrappedDate, formatter: itemFormatter) ")
}
}
.onDelete(perform: deleteSessions)
.padding()
}
}
}
}
And in my second view I have something like that:
struct DetailPartieSelecUIView: View {
#State var session:GameSession
#Environment(\.managedObjectContext) var moc
var body: some View {
Section("Ma session du \(session.wrappedDate, formatter: itemFormatter)"){
ForEach(session.playersArray, id: \.self) { player in
HStack {
Text(player.wrappedName) // OK it works
TextField("score", text : player.wrappedScore_part1) // it generates an error
TextField("score", text : player.wrappedScore_part2) // it generates an error
TextField("score", text : player.wrappedScore_part3) // it generates an error
}
}
}
}
}
private let itemFormatter: DateFormatter = {
let formatter = DateFormatter()
// formatter.dateStyle = .short
// formatter.timeStyle = .medium
formatter.dateFormat = "YYYY/MM/dd" //"YY/MM/dd"
return formatter
}()
also,
I have defined the "wrappedScore_part1","wrappedScore_part2","wrappedScore_part3" in the Player+CoreDataProperties.swift file
and "wrappedPlace", "wrappedData" as well as the "PlayersArray" in the GameSession+CoreDataProperties.swift file
it is done like that:
public var wrappedPlace: String {
place ?? "Unknown"
}
// Convert NSSet into an array of "Player" object
public var playersArray: [Player] {
let playersSet = players as? Set<Player> ?? []
return playersSet.sorted {
$0.wrappedName< $1.wrappedName
}
}
I am new at coding with swiftUI so I am probably doing something wrong... If anyone can help me it would be much appreciated.
Thanks a lot
I have tried a lot of things. Like changing the type of my attribute to Int32 instead os String. As I am suppose to enter numbers in those fields, I thought it would be best to have Integer. But it didn't change anything. and ultimately I had the same kind of error message
I tried also to add the $ symbol, like that:
TextField("score", text : player.$wrappedScore_part1)
But then I had other error message popping up at the row of my "ForEach", saying "Cannot convert value of type '[Player]' to expected argument type 'Binding'"
And also on the line just after the HStack, I had an error saying "Initializer 'init(_:)' requires that 'Binding' conform to 'StringProtocol'"
Thank you for your help!
Best regards,
JB
Your first problem of how to fetch the players in a session you need to supply a predicate to the #FetchRequest<Player>, e.g.
#FetchRequest
private var players: FetchedResults<Player>
init(session: Session) {
let predicate = NSPredicate(format: "session = %#", session)
let sortDescriptors = [SortDescriptor(\Player.timestamp)] // need something to sort by.
_players = FetchRequest(sortDescriptors: sortDescriptors, predicate: predicate)
}
That acts like a filter and will only return the players that have the session relation equalling that object. The reason you have to fetch like this is so any changes will be detected.
The second problem about the bindings can be solved like this:
struct PlayerView: View{
#ObservedObject var player: Player {
var body:some View {
if let score = Binding($player.score) {
TextField("Score", score)
}else{
Text("Player score missing")
}
}
}
This View takes the player object as an ObservedObject so body will be called when any of its properties change and allows you to get a binding to property. The Binding init takes an optional binding and returns a non-optional, allowing you to use it with a TextField.
So, I'm going through the SwiftUI documentation to get familiar. I was working on a grid sample app. It has the following code:
ForEach(allColors, id: \.description) { color in
Button {
selectedColor = color
} label: {
RoundedRectangle(cornerRadius: 4.0)
.aspectRatio(1.0, contentMode: ContentMode.fit)
.foregroundColor(color)
}
.buttonStyle(.plain)
}
It didn't occur to me first that ForEach is actually a struct, I thought it's a variation of the for in loop at first so I'm quite new at this. Then I checked the documentation.
When I read the documentation and some google articles for the ForEach struct, I didn't understand two points in the code:
So we are initializing the foreach struct with an array of colors. For the the ID why did they use .\description instead of .self?
Second is using color in. Since foreach is a struct and the paranthesis is the initializtion parameters this looks like the return type of a closure but why would we return individual colors to foreach? I thought the return is a collection of views or controls like button and label. This is like var anInteger: Int = 1 for example. What type does ForEach accept as a result of the closure? Or am I reading this all wrong?
So we are initializing the foreach struct with an array of colors. For the the ID why did they use .\description instead of .self?
It depends on the type of allColors. What you should have in mind that id here is expected to be stable. The documentation states:
It’s important that the id of a data element doesn’t change unless you replace the data element with a new data element that has a new identity. If the id of a data element changes, the content view generated from that data element loses any current state and animations.
So for example if colors are reference types (which are identifiable) and you swap one object with an identical one (in terms of field values), the identity will change, whereas description wouldn't (for the purposes of this example - just assuming intentions of code I have no access to).
Edit: Also note that in this specific example allColors appears to be a list of Color, which is not identifiable. So that's the reason behind the custom id keyPath.
Regarding your second point, note that the trailing closure is also an initialization parameter. To see this clearly we could use the "non-sugared" version:
ForEach(allColors, id: \.description, content: { color in
Button {
selectedColor = color
} label: {
RoundedRectangle(cornerRadius: 4.0)
.aspectRatio(1.0, contentMode: ContentMode.fit)
.foregroundColor(color)
}
.buttonStyle(.plain)
})
where content is a closure (an anonymous function) that gets passed an element of the collection and returns some View.
So the idea is something like this: "Give me an collection of identifiable elements and I will call a function for each of these elements expecting from you to return me some View".
I hope that this makes (some) sense.
Additional remarks regarding some of the comments:
It appears to me that the main source of confusion is the closure itself. So let's try something else. Let's write the same code without a closure:
ForEach's init has this signature:
init(_ data: Data, id: KeyPath<Data.Element, ID>, content: #escaping (Data.Element) -> Content)
Now, the content translates to:
A function with one parameter of type Data.Element, which in our case is inferred from the data so it is a Color. The function's return type is Content which is a view builder that produces some View
so our final code, which is equivalent to the first one, could look like this:
struct MyView: View {
let allColors: [Color] = [.red, .green, .blue]
#State private var selectedColor: Color?
var body: some View {
List {
ForEach(allColors, id: \.description, content: colorView)
}
}
#ViewBuilder
func colorView(color: Color) -> some View {
Button {
selectedColor = color
} label: {
RoundedRectangle(cornerRadius: 4.0)
.aspectRatio(1.0, contentMode: ContentMode.fit)
.foregroundColor(color)
}
.buttonStyle(.plain)
}
}
I hope that this could help to clarify things a little bit better.
I am using AttributedString in SwiftUI (Mac application) to customize the appearance of portions of a long string. I'm displaying the text formatted successfully and it appears correct.
My code looks like this:
struct TextView: View {
var body: some View {
ScrollView {
Text(tag())
}.padding()
}
func tag() -> AttributedString {
// code which creates the attributed string and applies formatting to various locations
}
}
At this point I want to add "touch points" ("interactive points") to the text (imagine hyperlinks) which will provide additional information when particular locations (pieces of text) are interacted with.
Ive seen some similar questions describing usage (or combinations) of NSTextAttachment , NSAttributedStringKey.link , UITextViewDelegate
see:
NSAttributedString click event in UILabel using Swift
but this isn't (or at least not obvious) the idiomatic "SwiftUI" way and seems cumbersome.
I would want to tag the string with the formatting while adding the "Attachment" which can be recognized in the view event handler:
func tag() -> AttributedString {
// loose for this example
var attributedString = AttributedString("My string which is very long")
for range in getRangesOfAttributes {
attributedString[range].foregroundColor = getRandomColor()
attributedString[range].attachment = Attachment() <<<<<<< this is missing, how do I tag this portion and recognize when it got interacted with in the View
}
}
func getRangesOfAttributes() -> ClosedRange<AttributedString.Index> {
... returns a bunch of ranges which need to be tagged
}
// the view can now do something once the attachment is clicked
var body: View {
Text(tag())
.onClickOfAttachment(...) // <<<< This is contrived, how can I do this?
}
[RESOLVED]
I am using a codable struct which stores the object values retrieved from an API call so I have amended my TextField using Cenk Belgin's example, I've also removed extra bits I've added in so if anyone else is trying to do the same thing then they won't have pieces of code from my app that aren't required.
TextField("Product Code", text: $item.ProdCode)
.onReceive(item.ProdCode.publisher.collect()) {
self.item.ProdCode = String($0.prefix(5))
}
Here is one way, not sure if it was mentioned in the other examples you gave:
#State var text = ""
var body: some View {
TextField("text", text: $text)
.onReceive(text.publisher.collect()) {
self.text = String($0.prefix(5))
}
}
The text.publisher will publish each character as it is typed. Collect them into an array and then just take the prefix.
From iOS 14 you can add onChange modifier to the TextField and use it like so :
TextField("Some Placeholder", text: self.$someValue)
.onChange(of: self.someValue, perform: { value in
if value.count > 10 {
self.someValue = String(value.prefix(10))
}
})
Works fine for me.
You can also do it in the Textfield binding directly:
TextField("Text", text: Binding(get: {item.ProCode}, set: {item.ProCode = $0.prefix(5).trimmingCharacters(in: .whitespacesAndNewlines)}))
Ok -
I want a picker view to pick one operator: "=","<",">"
This operator will be sent as a binding:
#Binding var op:String
My Picker:
Picker(selection: binding, label: Text("Query Type")) {
ForEach(0..<self.operators.count) { index in
Text(self.operators[index]).tag(index)
}
}.pickerStyle(SegmentedPickerStyle())
.padding()
Now My Binding with CallBack:
let binding = Binding<Int>(
get: {
return self.pickerSelection
},
set: {
//pickerSelection = $0
print("SETTTING: \($0)")
self.op = self.operators[self.pickerSelection]
self.queryCallback()
})
So, I can set the pickers perfectly. BUT, when I go back to edit my data, the picker never can choose the existing bound operator, say "<"
I put in the init an:
pickerSelection = operators.firstIndex(opValue)
However this will just start an infinite loop as pickerSelection is a #State variable
Anyone have a solution?
This is a method that works. It uses Combine to make an observable one can use to trigger the needed events. Also I see how useful Combine is with SwiftUI
https://stackoverflow.com/a/57519105/810300