ui/app: (ios) relay system focus events

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

ui/app/os_ios.go

@@ -110,6 +110,12 @@ func onDestroy(view C.CFTypeRef) {
 	w.view = 0
 }
 
+//export onFocus
+func onFocus(view C.CFTypeRef, focus int) {
+	w := views[view]
+	w.w.event(key.Focus{Focus: focus != 0})
+}
+
 //export onLowMemory
 func onLowMemory() {
 	runtime.GC()

ui/app/os_ios.m

@@ -36,6 +36,16 @@ static void redraw(CFTypeRef viewRef, BOOL sync) {
 	GioViewController *controller = [[GioViewController alloc] initWithNibName:nil bundle:nil];
 	controller.screen = self.window.screen;
     self.window.rootViewController = controller;
+	[[NSNotificationCenter defaultCenter] addObserverForName:UIWindowDidBecomeKeyNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *notification) {
+		UIView *view = self.window.rootViewController.view;
+		if (view != nil)
+			onFocus((__bridge CFTypeRef)view, YES);
+	}];
+	[[NSNotificationCenter defaultCenter] addObserverForName:UIWindowDidResignKeyNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *notification) {
+		UIView *view = self.window.rootViewController.view;
+		if (view != nil)
+			onFocus((__bridge CFTypeRef)view, NO);
+	}];
     [self.window makeKeyAndVisible];
 	return YES;
 }