Is didSet on a @Binding file specific?

Essentially, I’m nesting @Binding 3 layers deep.

struct LayerOne: View {
    @State private var doubleValue = 0.0
    
    var body: some View {
        LayerTwo(doubleValue: $doubleValue)
    }
}

struct LayerTwo: View {
    @Binding var doubleValue: Double {
        didSet {
            print(doubleValue)
        }
    }
    
    var body: some View {
        LayerThree(doubleValue: $doubleValue)
    }
}

struct LayerThree: View {
    @Binding var doubleValue: Double {
        didSet {
            print(doubleValue) // Only this print gets run when doubleValue is updated from this struct
        }
    }

    var body: Some view {
        // Button here changes doubleValue
    }
}

Whichever struct I change doubleValue in is the one where the didSet will get run, so for example if I change it in LayerThree only that one will print, none of the others will.

I am able to watch for changes with .onChange(of: doubleValue) which will then get run when it changes but it’s not making sense to me why didSet won’t get run except on the struct where it’s changed from.

Is @Binding struct specific?

>Solution :

Using property observers like didSet on values wrapped in PropertyWrappers will not have the "normal" effect because the value is being set inside the wrapper.

In SwiftUI, if you want to trigger an action when a value changes, you should use the onChange(of:perform:) modifier.

struct LayerTwo: View {
    @Binding var doubleValue: Double
    
    var body: some View {
        LayerThree(doubleValue: $doubleValue)
          .onChange(of: doubleValue) { newValue 
            print(newValue)
          }
    }
}