Problem with use of Binding

Question

nickthat Author

Level 1

4 points

Problem with use of Binding

import SwiftUI

@main

struct MagnatoshApp: App {

var body: some Scene {

@Binding var b : Double

@State var fullDescStr = ""

var fullDesc : Binding<String> = Binding<String>(projectedValue: $fullDescStr)

WindowGroup {

ContentView(cmd: "", output: "", commandDesc: "", selCommand: Binding<Command?>(nil), description: "dddd" )

}

the line

@Binding var b : Double

gives the error

Missing argument for parameter 'projectedValue' in property wrapper initializer; add 'wrappedValue' and 'projectedValue' arguments in '@Binding(...)'

I have been at this for hours trying different combinations which end up going down a long series of code changes which get me nowhere

I think this is a compiler bug.Trying to find a work around is difficult

Posted on Jan 7, 2024 9:53 AM

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Answer 1

Jan 8, 2024 1:36 PM in response to nickthat

Where do you give the binding b its value? What does b represent in the app?

Usually you give a binding its value by passing the value from a parent view. But you declared the binding in the App struct so there is no parent view. I don't know of any way you can give the binding b its value to use in the App struct.

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Answer 2

nickthat Author

Level 1

4 points

Jan 8, 2024 1:56 PM in response to Mark Szymczyk

The variable b didn't represent anything. It was a dummy variable put in to solve the real problem. I continued trying to get this to compile and in the end I do believe I fixed it by using a @State var instead of @Binding and did move it out of the App view too and subsequent compiler errors eventually lead me to a clean working build. I was coding in the dark because I didn't fully read up on State and Binding before turning my head towards them. I've only been programming with Swift for 2 weeks but have been a coder for 30 years or so. I intend to read up on them very soon but for now I can put the problem to bed. I shouldn't have been so hasty to blame the compiler. I think Swift is a very well thought out language and bow my head in shame for my insolence :-). Thanks for your help.

Sean

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Answer 3

Jun 19, 2024 9:13 AM in response to nickthat

Do you mind telling me how you fix it I came across the same issue an I was wondering if you could let me know how you fixed it. Please and thank you.

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Problem with use of Binding

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