From ffe86eef04f4e44d6a974dcade45527364265556 Mon Sep 17 00:00:00 2001
From: Zach Coleman <ztc0611@gmail.com>
Date: Wed, 22 Nov 2023 11:43:40 -0500
Subject: [PATCH] [iOS] Add APP_PAUSED and APP_RESUMED MainLoop notifications

---
 doc/classes/MainLoop.xml        |  5 +++--
 doc/classes/Node.xml            |  5 +++--
 platform/iphone/app_delegate.mm |  8 ++++++++
 platform/iphone/os_iphone.h     |  3 +++
 platform/iphone/os_iphone.mm    | 20 ++++++++++++++++++++
 5 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/doc/classes/MainLoop.xml b/doc/classes/MainLoop.xml
index 3092c822019..daeb1793f7e 100644
--- a/doc/classes/MainLoop.xml
+++ b/doc/classes/MainLoop.xml
@@ -201,11 +201,12 @@
 		</constant>
 		<constant name="NOTIFICATION_APP_RESUMED" value="1014">
 			Notification received from the OS when the app is resumed.
-			Specific to the Android platform.
+			Specific to mobile platforms.
 		</constant>
 		<constant name="NOTIFICATION_APP_PAUSED" value="1015">
 			Notification received from the OS when the app is paused.
-			Specific to the Android platform.
+			Specific to mobile platforms.
+			[b]Note:[/b] On iOS, you only have approximately 5 seconds to finish a task started by this signal. If you go over this allotment, iOS will kill the app instead of pausing it.
 		</constant>
 	</constants>
 </class>
diff --git a/doc/classes/Node.xml b/doc/classes/Node.xml
index 827accb47a6..ad3f7e2aa59 100644
--- a/doc/classes/Node.xml
+++ b/doc/classes/Node.xml
@@ -928,11 +928,12 @@
 		</constant>
 		<constant name="NOTIFICATION_APP_RESUMED" value="1014">
 			Notification received from the OS when the app is resumed.
-			Specific to the Android platform.
+			Specific to mobile platforms.
 		</constant>
 		<constant name="NOTIFICATION_APP_PAUSED" value="1015">
 			Notification received from the OS when the app is paused.
-			Specific to the Android platform.
+			Specific to mobile platforms.
+			[b]Note:[/b] On iOS, you only have approximately 5 seconds to finish a task started by this signal. If you go over this allotment, iOS will kill the app instead of pausing it.
 		</constant>
 		<constant name="PAUSE_MODE_INHERIT" value="0" enum="PauseMode">
 			Inherits pause mode from the node's parent. For the root node, it is equivalent to [constant PAUSE_MODE_STOP]. Default.
diff --git a/platform/iphone/app_delegate.mm b/platform/iphone/app_delegate.mm
index b0540f6a7fc..1dcd0b01945 100644
--- a/platform/iphone/app_delegate.mm
+++ b/platform/iphone/app_delegate.mm
@@ -145,6 +145,14 @@ static ViewController *mainViewController = nil;
 	OSIPhone::get_singleton()->on_focus_in();
 }
 
+- (void)applicationDidEnterBackground:(UIApplication *)application {
+	OSIPhone::get_singleton()->on_enter_background();
+}
+
+- (void)applicationWillEnterForeground:(UIApplication *)application {
+	OSIPhone::get_singleton()->on_exit_background();
+}
+
 - (void)dealloc {
 	self.window = nil;
 }
diff --git a/platform/iphone/os_iphone.h b/platform/iphone/os_iphone.h
index 013c3411e5f..3c18578b0a2 100644
--- a/platform/iphone/os_iphone.h
+++ b/platform/iphone/os_iphone.h
@@ -204,6 +204,9 @@ public:
 
 	void on_focus_out();
 	void on_focus_in();
+
+	void on_enter_background();
+	void on_exit_background();
 };
 
 #endif // IPHONE_ENABLED
diff --git a/platform/iphone/os_iphone.mm b/platform/iphone/os_iphone.mm
index 7b10d92c9b2..100590bfce5 100644
--- a/platform/iphone/os_iphone.mm
+++ b/platform/iphone/os_iphone.mm
@@ -861,4 +861,24 @@ void OSIPhone::on_focus_in() {
 	}
 }
 
+void OSIPhone::on_enter_background() {
+	// Do not check for is_focused, because on_focus_out will always be fired first by applicationWillResignActive.
+
+	if (get_main_loop()) {
+		get_main_loop()->notification(MainLoop::NOTIFICATION_APP_PAUSED);
+	}
+
+	on_focus_out();
+}
+
+void OSIPhone::on_exit_background() {
+	if (!is_focused) {
+		on_focus_in();
+
+		if (get_main_loop()) {
+			get_main_loop()->notification(MainLoop::NOTIFICATION_APP_RESUMED);
+		}
+	}
+}
+
 #endif