TemporaryStateBinding

TemporaryState.swift

@propertyWrapper
struct TemporaryState<Value>: DynamicProperty {
    @State var modifiedValue: Value? = nil
    let currentValue: Value
    init(_ value: Value) {
        self.currentValue = value
    }
    
    var wrappedValue: Value {
        modifiedValue ?? currentValue
    }
    
    var projectedValue: Binding<Value> {
        Binding(get: { wrappedValue }, set: { modifiedValue = $0 })
    }
    
    var isModified: Bool {
        modifiedValue != nil
    }
    
    func discard() {
        modifiedValue = nil
    }
}

TemporaryStateBinding.swift

@propertyWrapper
struct TemporaryStateBinding<Value>: DynamicProperty {
    
    @State var modifiedValue: Value? = nil
    @Binding var currentValue: Value
    init(_ value: Binding<Value>) {
        self._currentValue = value
    }
    
    var wrappedValue: Value {
        modifiedValue ?? currentValue
    }
    
    var projectedValue: Binding<Value> {
        Binding(get: { wrappedValue }, set: { modifiedValue = $0 })
    }
    
    var isModified: Bool {
        modifiedValue != nil
    }
    
    func discard() {
        modifiedValue = nil
    }
    
    func save() {
        if let value = modifiedValue {
            currentValue = value
            modifiedValue = nil
        }
    }
}

TemporaryStateBindingExample.swift

struct CountStepper: View {
    @TemporaryStateBinding var count: Int
    init(count: Binding<Int>) {
        self._count = TemporaryStateBinding(count)
    }
    
    var body: some View {
        VStack {
            Stepper("Count: \(count)", value: $count)
            Button("Save", action: _count.save)
            Button("Cancel", action: _count.discard)
        }
    }
}

struct ContentView: View {
    @State var count: Int = 0
    
    var body: some View {
        VStack {
            CountStepper(count: $count)
            Spacer().frame(height: 50)
            Text("Saved Count: \(count)")
            Button("Reset", action: { count = 0 })
        }
    }
}