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Suppress window-level safe-area on outer snapshot VC stack #8

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Suppress window-level safe-area on outer snapshot VC stack #8

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25 changes: 23 additions & 2 deletions Sources/SnapshotPreviewsCore/View+Snapshot.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -94,13 +94,19 @@ extension View {
}

private static func setupRootVC(subVC: UIViewController) -> UIViewController {
let windowRootVC = UIViewController()
// UIKit child VCs hosted inside a SwiftUI #Preview still receive window-level safeAreaInsets
// through the parent-VC chain; negating them here zeroes the effective inset for every descendant.
let windowRootVC = SafeAreaSuppressingViewController()
windowRootVC.view.bounds = UIScreen.main.bounds
windowRootVC.view.backgroundColor = .clear
windowRootVC.view.insetsLayoutMarginsFromSafeArea = false
windowRootVC.view.directionalLayoutMargins = .zero

let containerVC = UIViewController()
let containerVC = SafeAreaSuppressingViewController()
containerVC.view.backgroundColor = .clear
containerVC.view.translatesAutoresizingMaskIntoConstraints = false
containerVC.view.insetsLayoutMarginsFromSafeArea = false
containerVC.view.directionalLayoutMargins = .zero
windowRootVC.view.addSubview(containerVC.view)
windowRootVC.addChild(containerVC)
containerVC.didMove(toParent: windowRootVC)
Expand Down Expand Up @@ -254,4 +260,19 @@ extension CALayer {
return false
}
}

private final class SafeAreaSuppressingViewController: UIViewController {
// Negate any window-derived safeAreaInsets so descendants — including UIKit child VCs
// wrapped by the SwiftUI #Preview bridge — see effective insets of zero. UIKit clamps
// additionalSafeAreaInsets-adjusted insets to >= 0, so this just zeroes the resolved value.
override func viewSafeAreaInsetsDidChange() {
super.viewSafeAreaInsetsDidChange()
let windowInsets = view.window?.safeAreaInsets ?? .zero
additionalSafeAreaInsets = UIEdgeInsets(
top: -windowInsets.top,
left: -windowInsets.left,
bottom: -windowInsets.bottom,
right: -windowInsets.right)
}
}
#endif