feat: SwiftUI support for screen shielding

README.md

@@ -1,32 +1,38 @@
 # ScreenShieldKit
 
-A Swift package to protect sensitive content from screenshots and screen recording on iOS and macOS platforms.
+A Swift package that protects sensitive content from screenshots and screen recordings across Apple platforms — for UIKit, AppKit, Core Animation, and **SwiftUI**.
 
 ## Overview
 
-ScreenShieldKit provides an easy-to-use API to prevent content from being captured in screenshots or screen recordings. This is especially useful for applications that display sensitive information such as:
+ScreenShieldKit hides selected content from screenshots, screen recordings, and other system captures while it stays fully visible on the device. This is useful for screens that display sensitive information such as:
 
-- Financial data
+- Financial data (balances, card numbers)
 - Personal identification information
+- One-time passcodes and authentication screens
 - Confidential documents
-- Authentication screens
+
+The protection is scoped: you protect only the views that contain secrets, and the rest of your UI is captured normally.
 
 ## Requirements
 
-- iOS 14.0+ / macOS 11.0+
+| Surface | Minimum OS |
+| --- | --- |
+| UIKit / AppKit / CALayer | iOS 14.0 · macOS 11.0 |
+| SwiftUI | iOS 16.0 · macOS 13.0 · tvOS 16.0 · watchOS 11.0 · visionOS 1.0 |
+
 - Swift 5.7+
 
 ## Installation
 
 ### Swift Package Manager
 
-Add ScreenShieldKit to your project through Xcode's Package Dependencies:
+Add ScreenShieldKit through Xcode's **File → Add Packages…** with the URL:
 
-1. In Xcode, select "File" → "Add Packages..."
-2. Enter the repository URL: `https://github.com/daangn/ScreenShieldKit.git`
-3. Choose the version you want to use
+```
+https://github.com/daangn/ScreenShieldKit.git
+```
 
-Or add it to your `Package.swift` file:
+Or add it to your `Package.swift`:
 
 ```swift
 dependencies: [
@@ -36,31 +42,99 @@ dependencies: [
 
 ## Usage
 
-### Basic Usage
+### SwiftUI
+
+Apply the `.screenShield(_:)` modifier to any view you want to hide from captures:
+
+```swift
+import ScreenShieldKit
+import SwiftUI
+
+Text(oneTimeCode)
+  .font(.system(.title, design: .monospaced))
+  .screenShield()
+```
+
+To protect several views at once, group them and apply the modifier a single time:
+
+```swift
+VStack {
+  AccountBalanceView()
+  CardNumberView()
+}
+.screenShield()
+```
+
+**Dynamic on/off**
+
+Pass a `Bool` that participates in SwiftUI state to toggle protection at runtime:
+
+```swift
+struct CardView: View {
+  @State private var isSensitive = true
+
+  var body: some View {
+    VStack {
+      Toggle("Protect content", isOn: $isSensitive)
+
+      Text("1234 5678 9012 3456")
+        .screenShield(isSensitive)
+    }
+  }
+}
+```
+
+Toggling protection preserves the wrapped content's identity: it never inserts or removes views based on the flag, so the content's `@State`, scroll position, focus, and in-flight animations are **not** reset when you switch protection on or off.
+
+### UIKit
 
 ```swift
 import ScreenShieldKit
 
-// iOS
 let view = UIView()
-view.setScreenShield(enabled: true) // Enable protection
+view.setScreenShield(enabled: true)   // Enable protection
+view.setScreenShield(enabled: false)  // Disable protection
+```
 
-// When protection is no longer needed
-view.setScreenShield(enabled: false) // Disable protection
+### AppKit
+
+```swift
+import ScreenShieldKit
 
-// macOS
 let view = NSView()
-view.setScreenShield(enabled: true) // Enable protection
+view.setScreenShield(enabled: true)   // The view must have a backing layer
+```
+
+### Core Animation
 
-// When protection is no longer needed
-view.setScreenShield(enabled: false) // Disable protection
+```swift
+import ScreenShieldKit
+
+layer.setScreenShield(enabled: true)
 ```
 
-## Important Notes
+## How it works
+
+ScreenShieldKit selects a mechanism per platform and OS version:
+
+| Path | OS | Mechanism |
+| --- | --- | --- |
+| SwiftUI (native) | iOS 18 / macOS 15 / tvOS 18 / watchOS 11 / visionOS 2+ | Activates SwiftUI's native capture-redaction reason in the environment. Fully transparent to layout; no hosting boundary. |
+| SwiftUI (legacy) | iOS 16–17 / macOS 13–14 / tvOS 16–17 / visionOS 1 | Hosts the content in a hosting controller and applies the Core Animation capture flag to its backing layer. |
+| UIKit / AppKit / CALayer | iOS 14+ / macOS 11+ | Applies the Core Animation capture flag directly to the layer. |
+
+The SwiftUI native path is preferred where available because it composes cleanly with SwiftUI layout and state. The legacy path re-hosts the content, but SwiftUI keeps propagating the ancestor environment across the hosting boundary, so `@Environment` values and `@EnvironmentObject` dependencies still reach the shielded content.
+
+## Important notes
+
+- **Private platform behavior.** ScreenShieldKit relies on private platform behavior that can change between OS releases. When the mechanism is unavailable on a device, the call becomes a safe no-op (it never crashes). **Verify capture protection on every OS version you support** — with screenshots, screen recordings, AirPlay mirroring, and any in-app capture flow that matters for your product.
+- **App Store.** The library avoids private selectors and private symbol references: the SwiftUI native path constructs the capture-redaction option value directly, and the Core Animation path resolves its property key at runtime. Even so, using private platform behavior carries review risk you should evaluate for your app.
+- **`privacySensitive` interaction (SwiftUI native path).** On the native path (iOS 18 / macOS 15 / tvOS 18 / watchOS 11 / visionOS 2+), the shielded subtree is forced non-privacy-sensitive — even when `isProtected` is `false` — so activating the capture-redaction reason never blanks the content on device. Avoid relying on `.privacySensitive()` inside a `.screenShield()` boundary. The legacy path does not apply this, since it hides via the layer flag rather than a redaction reason.
+- **macOS is best-effort.** On macOS, layer-level capture hiding may not hide content from every system capture path.
+
+## Sample
 
-- This library uses private APIs which may not be approved for App Store submission
-- The protection mechanism may change in future OS versions
-- For macOS, the view must have a backing layer for the protection to work
+The `Sample/` app has two tabs — a UIKit demo and a SwiftUI demo — both driving protection from a toggle. The sample targets iOS 16 so you can exercise the legacy and native SwiftUI paths on the OS versions you support.
 
 ## License
 

Sample/Sample.xcodeproj/project.pbxproj

@@ -251,7 +251,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 18.2;
+				IPHONEOS_DEPLOYMENT_TARGET = 16.0;
 				LOCALIZATION_PREFERS_STRING_CATALOGS = YES;
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
@@ -308,7 +308,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 18.2;
+				IPHONEOS_DEPLOYMENT_TARGET = 16.0;
 				LOCALIZATION_PREFERS_STRING_CATALOGS = YES;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;

Sample/Sample/AppDelegate.swift

@@ -2,7 +2,7 @@
 //  AppDelegate.swift
 //  Sample
 //
-//  Created by Ray on 5/12/25.
+//  Created by Kanghoon Oh on 5/12/25.
 //
 
 import UIKit

Sample/Sample/SceneDelegate.swift

@@ -2,9 +2,10 @@
 //  SceneDelegate.swift
 //  Sample
 //
-//  Created by Ray on 5/12/25.
+//  Created by Kanghoon Oh on 5/12/25.
 //
 
+import SwiftUI
 import UIKit
 
 final class SceneDelegate: UIResponder, UIWindowSceneDelegate {
@@ -17,8 +18,30 @@ final class SceneDelegate: UIResponder, UIWindowSceneDelegate {
   ) {
     guard let windowScene = (scene as? UIWindowScene) else { return }
     let window = UIWindow(windowScene: windowScene)
-    window.rootViewController = ViewController()
+    window.rootViewController = makeRootViewController()
     window.makeKeyAndVisible()
     self.window = window
   }
+
+  private func makeRootViewController() -> UIViewController {
+    let uikitTab = UINavigationController(rootViewController: ViewController())
+    uikitTab.tabBarItem = UITabBarItem(
+      title: "UIKit",
+      image: UIImage(systemName: "square.dashed"),
+      tag: 0
+    )
+
+    let swiftuiTab = UINavigationController(
+      rootViewController: UIHostingController(rootView: SwiftUIDemoView())
+    )
+    swiftuiTab.tabBarItem = UITabBarItem(
+      title: "SwiftUI",
+      image: UIImage(systemName: "swift"),
+      tag: 1
+    )
+
+    let tabBarController = UITabBarController()
+    tabBarController.viewControllers = [uikitTab, swiftuiTab]
+    return tabBarController
+  }
 }

Sample/Sample/SwiftUIDemoView.swift

@@ -0,0 +1,86 @@
+//
+//  SwiftUIDemoView.swift
+//  Sample
+//
+//  Created by Kanghoon Oh on 7/12/26.
+//
+
+import ScreenShieldKit
+import SwiftUI
+
+/// Demonstrates ScreenShieldKit's SwiftUI surface: the ``View/screenShield(_:)`` modifier applied to
+/// both a composed card and inline text, with dynamic on/off protection driven by `@State`.
+///
+/// Take a screenshot or start a screen recording while `Protect content` is on: the shielded views
+/// disappear from the capture while staying visible on the device.
+struct SwiftUIDemoView: View {
+  @State private var isProtected = true
+
+  var body: some View {
+    ScrollView {
+      VStack(spacing: 28) {
+        Toggle("Protect content", isOn: $isProtected)
+
+        // 1) Modifier on a composed view.
+        VStack(alignment: .leading, spacing: 8) {
+          sectionTitle(".screenShield(_:) on a card")
+          balanceCard
+            .screenShield(isProtected)
+        }
+
+        // 2) Modifier on inline text.
+        VStack(alignment: .leading, spacing: 8) {
+          sectionTitle(".screenShield(_:) on inline text")
+          Text("1234 5678 9012 3456")
+            .font(.system(.title3, design: .monospaced))
+            .frame(maxWidth: .infinity)
+            .padding()
+            .background(RoundedRectangle(cornerRadius: 12).fill(Color.secondary.opacity(0.12)))
+            .screenShield(isProtected)
+        }
+
+        Text(
+          "Take a screenshot or start a screen recording. The shielded content is hidden from the capture but stays visible here. Toggling protection keeps the views' state intact."
+        )
+        .font(.footnote)
+        .foregroundColor(.secondary)
+        .frame(maxWidth: .infinity, alignment: .leading)
+      }
+      .padding()
+    }
+    .navigationTitle("SwiftUI")
+  }
+
+  private func sectionTitle(_ text: String) -> some View {
+    Text(text)
+      .font(.subheadline.weight(.semibold))
+      .foregroundColor(.secondary)
+  }
+
+  private var balanceCard: some View {
+    VStack(alignment: .leading, spacing: 6) {
+      Text("Account balance")
+        .font(.caption)
+        .foregroundColor(.white.opacity(0.8))
+      Text("$ 128,400.00")
+        .font(.largeTitle.bold())
+        .foregroundColor(.white)
+    }
+    .frame(maxWidth: .infinity, alignment: .leading)
+    .padding()
+    .background(
+      RoundedRectangle(cornerRadius: 16)
+        .fill(LinearGradient(
+          colors: [.blue, .purple],
+          startPoint: .topLeading,
+          endPoint: .bottomTrailing
+        ))
+    )
+  }
+}
+
+#Preview {
+  NavigationView {
+    SwiftUIDemoView()
+  }
+}