Expose deferred screen edges setting for ios devices (#18729)

# Objective

- This just exposes the preferred [screen edges deferring system
gestures](https://developer.apple.com/documentation/uikit/uiviewcontroller/preferredscreenedgesdeferringsystemgestures)
setting from
[winit](https://docs.rs/winit/latest/winit/platform/ios/trait.WindowExtIOS.html#tymethod.set_preferred_screen_edges_deferring_system_gestures),
making it accessible in bevy apps.

This setting is useful for ios apps that make use of the screen edges,
letting the app have control of the first edge gesture before relegating
to the os.


## Testing

- Tested on simulator and on an iPhone Xs

---

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Greeble <166992735+greeble-dev@users.noreply.github.com>
Co-authored-by: François Mockers <mockersf@gmail.com>

crates/bevy_window/src/window.rs

@@ -443,6 +443,17 @@ pub struct Window {
     ///
     /// [`WindowAttributesExtIOS::with_prefers_status_bar_hidden`]: https://docs.rs/winit/latest/x86_64-apple-darwin/winit/platform/ios/trait.WindowAttributesExtIOS.html#tymethod.with_prefers_status_bar_hidden
     pub prefers_status_bar_hidden: bool,
+    /// Sets screen edges for which you want your gestures to take precedence
+    /// over the system gestures.
+    ///
+    /// Corresponds to [`WindowAttributesExtIOS::with_preferred_screen_edges_deferring_system_gestures`].
+    ///
+    /// # Platform-specific
+    ///
+    /// - Only used on iOS.
+    ///
+    /// [`WindowAttributesExtIOS::with_preferred_screen_edges_deferring_system_gestures`]: https://docs.rs/winit/latest/x86_64-apple-darwin/winit/platform/ios/trait.WindowAttributesExtIOS.html#tymethod.with_preferred_screen_edges_deferring_system_gestures
+    pub preferred_screen_edges_deferring_system_gestures: ScreenEdge,
 }
 
 impl Default for Window {
@@ -487,6 +498,7 @@ impl Default for Window {
             titlebar_show_buttons: true,
             prefers_home_indicator_hidden: false,
             prefers_status_bar_hidden: false,
+            preferred_screen_edges_deferring_system_gestures: Default::default(),
         }
     }
 }
@@ -1444,6 +1456,31 @@ impl Default for EnabledButtons {
 #[derive(Component, Default)]
 pub struct ClosingWindow;
 
+/// The edges of a screen. Corresponds to [`winit::platform::ios::ScreenEdge`].
+///
+/// # Platform-specific
+///
+/// - Only used on iOS.
+///
+/// [`winit::platform::ios::ScreenEdge`]: https://docs.rs/winit/latest/x86_64-apple-darwin/winit/platform/ios/struct.ScreenEdge.html
+#[derive(Default, Debug, Clone, Copy, PartialEq, Eq, Hash, Reflect)]
+#[cfg_attr(feature = "serialize", derive(serde::Serialize, serde::Deserialize))]
+pub enum ScreenEdge {
+    #[default]
+    /// No edge.
+    None,
+    /// The top edge of the screen.
+    Top,
+    /// The left edge of the screen.
+    Left,
+    /// The bottom edge of the screen.
+    Bottom,
+    /// The right edge of the screen.
+    Right,
+    /// All edges of the screen.
+    All,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/bevy_winit/src/converters.rs

@@ -10,6 +10,9 @@ use bevy_window::SystemCursorIcon;
 use bevy_window::{EnabledButtons, WindowLevel, WindowTheme};
 use winit::keyboard::{Key, NamedKey, NativeKey};
 
+#[cfg(target_os = "ios")]
+use bevy_window::ScreenEdge;
+
 pub fn convert_keyboard_input(
     keyboard_input: &winit::event::KeyEvent,
     window: Entity,
@@ -718,3 +721,16 @@ pub fn convert_resize_direction(resize_direction: CompassOctant) -> winit::windo
         CompassOctant::SouthEast => winit::window::ResizeDirection::SouthEast,
     }
 }
+
+#[cfg(target_os = "ios")]
+/// Converts a [`bevy_window::ScreenEdge`] to a [`winit::platform::ios::ScreenEdge`].
+pub(crate) fn convert_screen_edge(edge: ScreenEdge) -> winit::platform::ios::ScreenEdge {
+    match edge {
+        ScreenEdge::None => winit::platform::ios::ScreenEdge::NONE,
+        ScreenEdge::Top => winit::platform::ios::ScreenEdge::TOP,
+        ScreenEdge::Bottom => winit::platform::ios::ScreenEdge::BOTTOM,
+        ScreenEdge::Left => winit::platform::ios::ScreenEdge::LEFT,
+        ScreenEdge::Right => winit::platform::ios::ScreenEdge::RIGHT,
+        ScreenEdge::All => winit::platform::ios::ScreenEdge::ALL,
+    }
+}

crates/bevy_winit/src/system.rs

@@ -568,6 +568,16 @@ pub(crate) fn changed_windows(
             if window.prefers_status_bar_hidden != cache.window.prefers_status_bar_hidden {
                 winit_window.set_prefers_status_bar_hidden(window.prefers_status_bar_hidden);
             }
+            if window.preferred_screen_edges_deferring_system_gestures
+                != cache
+                    .window
+                    .preferred_screen_edges_deferring_system_gestures
+            {
+                use crate::converters::convert_screen_edge;
+                let preferred_edge =
+                    convert_screen_edge(window.preferred_screen_edges_deferring_system_gestures);
+                winit_window.set_preferred_screen_edges_deferring_system_gestures(preferred_edge);
+            }
         }
         cache.window = window.clone();
     }

crates/bevy_winit/src/winit_windows.rs

@@ -145,7 +145,14 @@ impl WinitWindows {
 
         #[cfg(target_os = "ios")]
         {
+            use crate::converters::convert_screen_edge;
             use winit::platform::ios::WindowAttributesExtIOS;
+
+            let preferred_edge =
+                convert_screen_edge(window.preferred_screen_edges_deferring_system_gestures);
+
+            winit_window_attributes = winit_window_attributes
+                .with_preferred_screen_edges_deferring_system_gestures(preferred_edge);
             winit_window_attributes = winit_window_attributes
                 .with_prefers_home_indicator_hidden(window.prefers_home_indicator_hidden);
             winit_window_attributes = winit_window_attributes

examples/mobile/src/lib.rs

@@ -5,7 +5,7 @@ use bevy::{
     input::{gestures::RotationGesture, touch::TouchPhase},
     log::{Level, LogPlugin},
     prelude::*,
-    window::{AppLifecycle, WindowMode},
+    window::{AppLifecycle, ScreenEdge, WindowMode},
     winit::WinitSettings,
 };
 
@@ -34,6 +34,8 @@ pub fn main() {
                     prefers_home_indicator_hidden: true,
                     // Only has an effect on iOS
                     prefers_status_bar_hidden: true,
+                    // Only has an effect on iOS
+                    preferred_screen_edges_deferring_system_gestures: ScreenEdge::Bottom,
                     ..default()
                 }),
                 ..default()