//AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    // Override point for customization after application launch.    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];        self.window.backgroundColor=[UIColor whiteColor];        RootViewController *rootView=[[RootViewController alloc]init];        UINavigationController *nav = [[UINavigationController alloc]initWithRootViewController:rootView];        [_window setRootViewController:nav];        [nav release];    [rootView release];            return YES;}

//RootViewController.m- (void)viewDidLoad {    // Do any additional setup after loading the view.    [super viewDidLoad];    // Do any additional setup after loading the view.    [self.navigationController.navigationBar setTranslucent:NO];//设置navigationbar的半透明        self.title = @"RootViewController";//设置navigationbar上显示的标题        [self.navigationController.navigationBar setBarTintColor:[UIColor purpleColor]];//设置navigationbar的颜色        self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonItemStyleDone target:self action:Nil];//设置navigationbar左边按钮        self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonItemStylePlain target:self action:Nil];//设置navigationbar右边按钮        [self.navigationController.navigationBar setTintColor:[UIColor whiteColor]];//设置navigationbar上左右按钮字体颜色         //self.navigationItem.rightBarButtonItem setTarget:<#(id)#>    //动态添加一个按钮         UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];        button.frame = CGRectMake(0, 300, 300, 50);        [button setTitle:@"新添加的动态按钮" forState: UIControlStateNormal];        button.backgroundColor = [UIColor clearColor];        button.tag = 2000;        [button addTarget:self action:@selector(clicked:) forControlEvents:UIControlEventTouchUpInside];        [self.view addSubview:button];    }- (void)clicked:(id) sender{    SecondViewController *second = [[SecondViewController alloc]init];    [self.navigationController pushViewController:second animated:YES];    //second.str = @"hello!!";    [second release];}//这个是新按钮的响应函数-(IBAction) buttonClicked:(id)sender {    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示"                                                    message:@"单击了动态按钮！"                                                   delegate:self                                          cancelButtonTitle:@"确定"                                          otherButtonTitles:nil];    [alert show];    [alert release];}