From bc68893ce1f214133fdf134aae10bf196d3bbdb3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cihat=20G=C3=BCnd=C3=BCz?= <jeehut@fline.dev>
Date: Tue, 13 Oct 2026 13:11:05 +0200
Subject: [PATCH] Write the inverted value through a negated Bool binding

The setter of `!binding` wrote the new value unchanged into the
original binding, so toggling a control bound to `!$isOff` stored the
opposite of what the user chose.
---
 .../HandySwiftUI/Extensions/BindingExt.swift  |  2 +-
 Tests/HandySwiftUITests/BindingExtTests.swift | 22 +++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 Tests/HandySwiftUITests/BindingExtTests.swift

diff --git a/Sources/HandySwiftUI/Extensions/BindingExt.swift b/Sources/HandySwiftUI/Extensions/BindingExt.swift
index d8287ea..f1f7857 100644
--- a/Sources/HandySwiftUI/Extensions/BindingExt.swift
+++ b/Sources/HandySwiftUI/Extensions/BindingExt.swift
@@ -17,7 +17,7 @@ import SwiftUI
 public prefix func ! (value: Binding<Bool>) -> Binding<Bool> {
    Binding<Bool>(
       get: { !value.wrappedValue },
-      set: { value.wrappedValue = $0 }
+      set: { value.wrappedValue = !$0 }
    )
 }
 
diff --git a/Tests/HandySwiftUITests/BindingExtTests.swift b/Tests/HandySwiftUITests/BindingExtTests.swift
new file mode 100644
index 0000000..6ebaa94
--- /dev/null
+++ b/Tests/HandySwiftUITests/BindingExtTests.swift
@@ -0,0 +1,22 @@
+import SwiftUI
+import Testing
+
+@testable import HandySwiftUI
+
+@MainActor
+struct BindingExtTests {
+   @Test
+   func negatedBindingWritesTheInvertedValue() {
+      var stored = false
+      let binding = Binding(get: { stored }, set: { stored = $0 })
+      let negated = !binding
+
+      #expect(negated.wrappedValue == true)
+
+      negated.wrappedValue = false
+      #expect(stored == true)
+
+      negated.wrappedValue = true
+      #expect(stored == false)
+   }
+}