UINavigationBar设置全局导航条风格和颜色

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    
    _window=[[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    
    _window.backgroundColor =[UIColor colorWithRed:249/255.0 green:249/255.0 blue:249/255.0 alpha:1];

    //设置全局导航条风格和颜色
    [[UINavigationBar appearance] setBarTintColor:[UIColor colorWithRed:23/255.0 green:180/255.0 blue:237/255.0 alpha:1]];
    [[UINavigationBar appearance] setBarStyle:UIBarStyleBlack];
    
    KCFriendViewController *friendController=[[KCFriendViewController alloc]init];
    UINavigationController *navigationController=[[UINavigationController alloc]initWithRootViewController:friendController];
    
    _window.rootViewController=navigationController;
    
    [_window makeKeyAndVisible];
    
    return YES;
}