osx 代码创建自定义NSMenu & NSMenuItem

//    unichar arrowKey = 'r';    NSString *refresh = [NSString stringWithCharacters:&arrowKey length:1];    //    //    NSString *homePage = [NSString stringWithFormat:@"^%c",arrowKey1];    unichar arrowKey2 = 'o';    NSString *homePage = [NSString stringWithCharacters:&arrowKey2 length:1];        //    unichar arrowKey3 = 27;    NSString *esc = [NSString stringWithCharacters:&arrowKey3 length:1];            NSMenuItem *item= [NSApp.mainMenu insertItemWithTitle:@"111" action:nil keyEquivalent:@"" atIndex:1];    NSMenu *submenu=[[NSMenu alloc] initWithTitle:@"ww"];    item.submenu=submenu;    [submenu addItemWithTitle:@"1" action:@selector(dd) keyEquivalent:homePage];//返回首页    [submenu addItemWithTitle:@"2" action:@selector(dd) keyEquivalent:refresh];//刷新    [submenu addItemWithTitle:@"3" action:@selector(dd) keyEquivalent:esc];//exit