Add stubs for NSUserNotificationCenter

include/Foundation/NSUserNotification.h

@@ -25,10 +25,19 @@
 @interface NSUserNotificationAction : NSObject <NSCopying>
 @end
 
-@interface NSUserNotificationCenter : NSObject
-@end
-
 @protocol NSUserNotificationCenterDelegate <NSObject>
 @end
 
+@interface NSUserNotificationCenter : NSObject {
+    id<NSUserNotificationCenterDelegate> _delegate;
+}
+
+@property(class, readonly, strong) NSUserNotificationCenter *defaultUserNotificationCenter;
+@property(assign) id<NSUserNotificationCenterDelegate> delegate;
+
+- (void)deliverNotification:(NSUserNotification *)notification;
+- (void)removeDeliveredNotification:(NSUserNotification *)notification;
+
+@end
+
 FOUNDATION_EXPORT NSString * const NSUserNotificationDefaultSoundName;

src/NSUserNotification.m

@@ -40,6 +40,27 @@
 @end
 
 @implementation NSUserNotificationCenter
+
+static NSUserNotificationCenter *_defaultUserNotificationCenter = nil;
+
+@synthesize delegate = _delegate;
+
++ (NSUserNotificationCenter *)defaultUserNotificationCenter {
+	if (_defaultUserNotificationCenter == nil) {
+		_defaultUserNotificationCenter = [[NSUserNotificationCenter alloc] init];
+	}
+
+	return _defaultUserNotificationCenter;
+}
+
+- (void)deliverNotification:(NSUserNotification *)notification {
+	NSLog(@"[NSUserNotificationCenter deliverNotification:]");
+}
+
+- (void)removeDeliveredNotification:(NSUserNotification *)notification {
+	NSLog(@"[NSUserNotificationCenter removeDeliveredNotification:]");
+}
+
 @end
 
 NSString * const NSUserNotificationDefaultSoundName = @"DefaultSoundName";