Question 67934 in IOS Swift Question posted in
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Optional binding a color in swiftUI – Ios swift

I have a question about optional bindings in swiftUI. I have a struct:

struct LightPairing: View {
    @Binding var light: Color?
    init(light: Binding<Color?>) {
        self._light = light
    }
    // the rest of the code, such as body is omitted since it is very long
}

I want to give the light property a default value of nil, light: Binding<Color?> = nil, but it does not work. Is there anyway to get around this issue?

Edit: When I do:

light: Binding<Color?> = nil I get the error message saying

"Nil default argument value cannot be converted to type
Binding<Color?>"

Tags:

3

Answers


  1. 0

    A @Binding takes a value from another property, such as a @State property wrapper (a property that owns the value).

    You can either set the @Binding from a property in another struct (elsewhere)…

    @State private var lightElsewhere: Color? = nil

    then call…

    LightPairing(light: $lightElsewhere)

    or alternatively change your @Binding to a State property in this struct.

    @State private var light: Color? = nil

    Where this occurs will depend on your app logic.

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  2. 0

    Your property is of type Binding<Color?> so you can’t simply assign nil. You have to assign Binding<Color?> where the bound value is nil.

    You can do this via Binding.constant():

    struct LightPairing: View {
    @Binding var light: Color?
    init(light: Binding<Color?> = .constant(nil)) {
        self._light = light
    }
    // the rest of the code, such as body is omitted since it is very long
}

    Now, if you don’t provide a binding for light a default value will be supplied for you.

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  3. 0

    Try like below:-

    struct ContentView: View {
    
    var body: some View {
        LightPairing(light: .constant(nil))
    }
}
struct LightPairing: View {
    @Binding var light: Color?
    init(light: Binding<Color?>) {
        self._light = light
    }
    var body: some View {
        ZStack {
            //Some Code
        }
    }
    // the rest of the code, such as body is omitted since it is very long
}
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