SwiftUI Binding wrappers for willSet and didSet

Binding+didSet.swift

extension Binding {
    /// Wrapper to listen to didSet of Binding
    func didSet(_ didSet: @escaping ((newValue: Value, oldValue: Value)) -> Void) -> Binding<Value> {
        return .init(get: { self.wrappedValue }, set: { newValue in
            let oldValue = self.wrappedValue
            self.wrappedValue = newValue
            didSet((newValue, oldValue))
        })
    }
    
    /// Wrapper to listen to willSet of Binding
    func willSet(_ willSet: @escaping ((newValue: Value, oldValue: Value)) -> Void) -> Binding<Value> {
        return .init(get: { self.wrappedValue }, set: { newValue in
            willSet((newValue, self.wrappedValue))
            self.wrappedValue = newValue
        })
    }
}

Example.swift

struct FilterView: View {
    @Binding var filters: [String]
    @Binding var selectedFilters: Set<String>
    
    var body: some View {
        List(filters, id: \.self, selection: $selectedFilters.didSet {
            print("Selection changed from \($1) to \($0)")
        }, rowContent: { filter in
            Text(filter)
        })
    }
}

I know what @discardableResult does. I don't really understand how you think your code would work, like how does the original binding know about your handler closure?..

I tested it because you were very confident, it doesn't work.

@Amzd my apologies. Yeah, using the extension function in the .onAppear() hook doesn't work, true. But it still works as in the original use case you provided: ...selection: $selectedFilters.onChange... In any case, the original intention was to offer a more concise version of the code as the one you created.