app: [macOS] use NSNotificationCenter to receive app events

Notifications don't require a list of windows nor an app delegate.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/os_macos.go

@@ -851,20 +851,6 @@ func gio_onWindowed(view C.CFTypeRef) {
 	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
-//export gio_onAppHide
-func gio_onAppHide() {
-	for _, w := range viewMap {
-		w.setStage(StagePaused)
-	}
-}
-
-//export gio_onAppShow
-func gio_onAppShow() {
-	for _, w := range viewMap {
-		w.setStage(StageRunning)
-	}
-}
-
 //export gio_onFinishLaunching
 func gio_onFinishLaunching() {
 	close(launched)

app/os_macos.m

@@ -191,6 +191,12 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
     r = [self convertRect:r toView:nil];
     return [[self window] convertRectToScreen:r];
 }
+- (void)applicationWillUnhide:(NSNotification *)notification {
+	gio_onShow((__bridge CFTypeRef)self);
+}
+- (void)applicationDidHide:(NSNotification *)notification {
+	gio_onHide((__bridge CFTypeRef)self);
+}
 @end
 
 // Delegates are weakly referenced from their peers. Nothing
@@ -374,6 +380,15 @@ CFTypeRef gio_createView(void) {
 		GioView* view = [[GioView alloc] initWithFrame:frame];
 		view.wantsLayer = YES;
 		view.layerContentsRedrawPolicy = NSViewLayerContentsRedrawDuringViewResize;
+
+		[[NSNotificationCenter defaultCenter] addObserver:view
+												 selector:@selector(applicationWillUnhide:)
+													 name:NSApplicationWillUnhideNotification
+												   object:nil];
+		[[NSNotificationCenter defaultCenter] addObserver:view
+												 selector:@selector(applicationDidHide:)
+													 name:NSApplicationDidHideNotification
+												   object:nil];
 		return CFBridgingRetain(view);
 	}
 }
@@ -384,12 +399,6 @@ CFTypeRef gio_createView(void) {
 	[NSApp activateIgnoringOtherApps:YES];
 	gio_onFinishLaunching();
 }
-- (void)applicationDidHide:(NSNotification *)aNotification {
-	gio_onAppHide();
-}
-- (void)applicationWillUnhide:(NSNotification *)notification {
-	gio_onAppShow();
-}
 @end
 
 void gio_main() {