Slide Over: What Is It, Floating Window on iPad
Slide Over is a multitasking mode on iPad that displays a second app in a floating window on top of the main one. The window takes up about a quarter of the screen width, can be moved left or right, and can be hidden by swiping away. According to Apple Human Interface Guidelines (2025), Slide Over is available on all iPad models starting from iOS 9 and is part of the iPadOS multitasking system.
Key Takeaways
- Slide Over - a floating window of a second app on top of the main one on iPad.
- 25% width - the Slide Over window takes up about a quarter of the screen.
- Access - opened by swiping from the right edge of the screen or via the Dock.
- Flexibility - the window can be moved, hidden, and turned into Split View.
- Adaptation - the app in Slide Over gets Size Class Compact Width.
What Is Slide Over?
Slide Over is a multitasking mode exclusive to iPad that displays a second app in a narrow floating window. Unlike Split View, where the screen is divided into two equal parts, Slide Over sits on top of the main interface, allowing the user to quickly access reference materials, messengers, or a media player.
The mode was introduced in iOS 9 alongside Split View and was initially supported only on iPad Air 2, iPad mini 4, and iPad Pro. Today, Slide Over works on all iPad models, including the 10th-generation iPad and iPad mini (A17 Pro). For a developer, Slide Over means the app can be displayed in a window 320 pt wide - a compact Size Class.
The user opens Slide Over by swiping from the right edge of the screen or by dragging an icon from the Dock to the right side of the screen. Any app can be launched in the Slide Over window - no special support is required, although adapted apps look significantly better.
How Slide Over Works on iPad
Slide Over is implemented as a separate UIWindowScene on top of the main window. Each app in Slide Over gets its own UIWindowScene instance with a width of 320 pt (in portrait orientation). The user can have one app in Slide Over - launching a second one replaces the first.
The Slide Over window can be moved by dragging the special handle (pill) at the top of the window. If you drag the window to the left edge - it snaps to the left. If you swipe the window all the way to the right - it collapses into an invisible panel and is activated by swiping from the right edge. The system remembers the last app launched in Slide Over.
A key feature is that Slide Over can be transformed into Split View. If the user drags the Slide Over window to the top or bottom edge, the mode changes to Split View. Both apps then get a full screen split with equal shares.
Slide Over vs Split View: Differences
The main difference is in screen space distribution. Split View divides the screen into two equal or proportional parts, each app gets a fixed area. Slide Over does not take away space from the main app - it remains full-screen, and Slide Over is displayed on top.
The second difference is focus. In Split View, both apps are active and visible simultaneously. In Slide Over, the main app loses focus (gets onResignActive), while Slide Over gains focus and interactivity. When Slide Over is hidden, focus returns to the main app.
Third - the number of scenarios. Split View requires the developer to support multiple widths. Slide Over always has a width of 320 pt - a constant compact class. This simplifies development: only one adaptive layout for this size is needed.
| Characteristic | Slide Over | Split View |
|---|---|---|
| Window Size | 320 pt (fixed width) | 50%, 25%, or 75% of screen |
| Position | On top of the main app | Side by side, screen split |
| Focus | Only Slide Over is active | Both apps can be active |
| Size Class | Compact Width, Regular Height | Depends on the share |
Adapting Your App for Slide Over
To work correctly in Slide Over, the app must support the Compact Width Size Class. This means the interface must fit within 320 pt width. Apple's main recommendations: use Auto Layout with adaptive constraints, avoid fixed widths, test all screens in the iPad simulator with Slide Over.
In practice, adaptation comes down to using UIStackView or SwiftUI with VStack/HStack, which automatically adjust to the available space. Tables (UITableView) and collections (UICollectionView) work correctly in the app if their cells use self-sizing.
For UIKit, use UITraitCollection with a check for horizontalSizeClass. If the class equals .compact, switch the interface to a simplified version: remove extra columns, replace Sidebar with StackView. SwiftUI does this automatically via @Environment(\.horizontalSizeClass).
App Lifecycle in Slide Over
When an app opens in Slide Over, its UIScene receives the sceneWillEnterForeground notification. The scene then transitions to the foreground active state - just like in full-screen launch. There is no difference in the lifecycle between full-screen mode and Slide Over: sceneWillEnterForeground and sceneDidBecomeActive.
When transitioning from Slide Over back to full-screen mode or when the window is hidden, the scene receives sceneDidEnterBackground. If the user swipes Slide Over to the right (hides it), the app continues running in the background until another Slide Over app replaces it or the system frees up memory.
For apps that rely on sensors or the camera, Slide Over can be a problem. In Slide Over, the camera is unavailable, and the accelerometer may give incorrect readings. Check isDeviceOrientationLocked or forcibly lock the orientation when entering Slide Over.
Frequently Asked Questions
What width does the Slide Over window have?
In portrait orientation - 320 pt. In landscape orientation, the width may vary, but the horizontalSizeClass remains Compact. This is Apple's standard compact class.
Can I disable Slide Over for my app?
Yes, set UIApplicationSupportsMultipleScenes = NO in Info.plist. The app will only open in full-screen mode; Slide Over and Split View will be unavailable.
How many apps can run in Slide Over?
Only one. Launching a second app in Slide Over replaces the current one. iPad does not support multiple floating windows - this is a limitation of iPadOS.
How does Slide Over affect performance?
Both apps share the iPad's resources. For heavy apps (games, video), Slide Over may reduce frame rates. It is recommended to limit draw calls and disable animations if the app runs in Slide Over.
Is Slide Over supported on iPad mini?
Yes. On iPad mini with an 8.3-inch screen, Slide Over works in the same mode. Due to the smaller screen, the window takes up a larger percentage of space, but the UIScene behavior remains identical.
Summary
- Slide Over - a floating window of a second app on top of the main one on iPad.
- Width - 320 pt, Compact Width Size Class.
- Activation - swipe from the right edge of the screen or from the Dock.
- Difference from Split View - Slide Over does not split the screen but overlays on top.
- Transformation - Slide Over can become Split View by dragging to the edge.
- Lifecycle - standard UIScene lifecycle, foreground/background.
- Conclusion - Slide Over requires Compact Width support but does not require complex adaptation thanks to its fixed 320 pt width.
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