Enhance mobile suspend MainLoop notifications

doc/classes/MainLoop.xml

@@ -119,19 +119,20 @@
 		</constant>
 		<constant name="NOTIFICATION_APPLICATION_RESUMED" value="2014">
 			Notification received from the OS when the application is resumed.
-			Specific to the Android platform.
+			Specific to the Android and iOS platforms.
 		</constant>
 		<constant name="NOTIFICATION_APPLICATION_PAUSED" value="2015">
 			Notification received from the OS when the application is paused.
-			Specific to the Android platform.
+			Specific to the Android and iOS 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="NOTIFICATION_APPLICATION_FOCUS_IN" value="2016">
 			Notification received from the OS when the application is focused, i.e. when changing the focus from the OS desktop or a thirdparty application to any open window of the Godot instance.
-			Implemented on desktop platforms.
+			Implemented on desktop and mobile platforms.
 		</constant>
 		<constant name="NOTIFICATION_APPLICATION_FOCUS_OUT" value="2017">
 			Notification received from the OS when the application is defocused, i.e. when changing the focus from any open window of the Godot instance to the OS desktop or a thirdparty application.
-			Implemented on desktop platforms.
+			Implemented on desktop and mobile platforms.
 		</constant>
 		<constant name="NOTIFICATION_TEXT_SERVER_CHANGED" value="2018">
 			Notification received when text server is changed.

doc/classes/Node.xml

@@ -1151,19 +1151,20 @@
 		</constant>
 		<constant name="NOTIFICATION_APPLICATION_RESUMED" value="2014">
 			Notification received from the OS when the application is resumed.
-			Implemented only on Android.
+			Specific to the Android and iOS platforms.
 		</constant>
 		<constant name="NOTIFICATION_APPLICATION_PAUSED" value="2015">
 			Notification received from the OS when the application is paused.
-			Implemented only on Android.
+			Specific to the Android and iOS 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="NOTIFICATION_APPLICATION_FOCUS_IN" value="2016">
-			Notification received from the OS when the application is focused, i.e. when changing the focus from the OS desktop or a third-party application to any open window of the Godot instance.
-			Implemented on desktop platforms.
+			Notification received from the OS when the application is focused, i.e. when changing the focus from the OS desktop or a thirdparty application to any open window of the Godot instance.
+			Implemented on desktop and mobile platforms.
 		</constant>
 		<constant name="NOTIFICATION_APPLICATION_FOCUS_OUT" value="2017">
-			Notification received from the OS when the application is defocused, i.e. when changing the focus from any open window of the Godot instance to the OS desktop or a third-party application.
-			Implemented on desktop platforms.
+			Notification received from the OS when the application is defocused, i.e. when changing the focus from any open window of the Godot instance to the OS desktop or a thirdparty application.
+			Implemented on desktop and mobile platforms.
 		</constant>
 		<constant name="NOTIFICATION_TEXT_SERVER_CHANGED" value="2018">
 			Notification received when the [TextServer] is changed.

platform/android/os_android.cpp

@@ -324,11 +324,17 @@ void OS_Android::main_loop_end() {
 
 void OS_Android::main_loop_focusout() {
 	DisplayServerAndroid::get_singleton()->send_window_event(DisplayServer::WINDOW_EVENT_FOCUS_OUT);
+	if (OS::get_singleton()->get_main_loop()) {
+		OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_FOCUS_OUT);
+	}
 	audio_driver_android.set_pause(true);
 }
 
 void OS_Android::main_loop_focusin() {
 	DisplayServerAndroid::get_singleton()->send_window_event(DisplayServer::WINDOW_EVENT_FOCUS_IN);
+	if (OS::get_singleton()->get_main_loop()) {
+		OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_FOCUS_IN);
+	}
 	audio_driver_android.set_pause(false);
 }
 

platform/ios/app_delegate.mm

@@ -167,6 +167,14 @@ - (void)applicationDidBecomeActive:(UIApplication *)application {
 	OS_IOS::get_singleton()->on_focus_in();
 }
 
+- (void)applicationDidEnterBackground:(UIApplication *)application {
+	OS_IOS::get_singleton()->on_enter_background();
+}
+
+- (void)applicationWillEnterForeground:(UIApplication *)application {
+	OS_IOS::get_singleton()->on_exit_background();
+}
+
 - (void)dealloc {
 	self.window = nil;
 }

platform/ios/os_ios.h

@@ -129,6 +129,9 @@ class OS_IOS : public OS_Unix {
 
 	void on_focus_out();
 	void on_focus_in();
+
+	void on_enter_background();
+	void on_exit_background();
 };
 
 #endif // IOS_ENABLED

platform/ios/os_ios.mm

@@ -601,6 +601,10 @@ void register_dynamic_symbol(char *name, void *address) {
 			DisplayServerIOS::get_singleton()->send_window_event(DisplayServer::WINDOW_EVENT_FOCUS_OUT);
 		}
 
+		if (OS::get_singleton()->get_main_loop()) {
+			OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_FOCUS_OUT);
+		}
+
 		[AppDelegate.viewController.godotView stopRendering];
 
 		audio_driver.stop();
@@ -615,10 +619,34 @@ void register_dynamic_symbol(char *name, void *address) {
 			DisplayServerIOS::get_singleton()->send_window_event(DisplayServer::WINDOW_EVENT_FOCUS_IN);
 		}
 
+		if (OS::get_singleton()->get_main_loop()) {
+			OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_FOCUS_IN);
+		}
+
 		[AppDelegate.viewController.godotView startRendering];
 
 		audio_driver.start();
 	}
 }
 
+void OS_IOS::on_enter_background() {
+	// Do not check for is_focused, because on_focus_out will always be fired first by applicationWillResignActive.
+
+	if (OS::get_singleton()->get_main_loop()) {
+		OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_PAUSED);
+	}
+
+	on_focus_out();
+}
+
+void OS_IOS::on_exit_background() {
+	if (!is_focused) {
+		on_focus_in();
+
+		if (OS::get_singleton()->get_main_loop()) {
+			OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_RESUMED);
+		}
+	}
+}
+
 #endif // IOS_ENABLED