Nevermind i got it with this little code modification:
NSMenu* mainMenu = [NSApp mainMenu];
NSMenu* debugMenu = [[NSMenu alloc] initWithTitle:@"Menu"];
NSMenuItem* newItem = [[NSMenuItem alloc] initWithTitle:@"Item" action:nil keyEquivalent:@""];
[newItem setSubmenu:debugMenu];
[mainMenu addItem:newItem];
[debugMenu addItemWithTitle:@"Run Unit Tests" action:nil keyEquivalent:@""];