页面间跳转和传值

self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    FirstViewController *rootView=[[[FirstViewController alloc]init]autorelease];
    self.navController=[[[UINavigationController alloc]init]autorelease];
    [self.navController pushViewController:rootView animated:YES];
    [self.window addSubview:self.navController.view];
    [self.window makeKeyAndVisible];

SecondViewController *SecondView= [[[SecondViewController alloc] init]autorelease];
    SecondView.str=_tf01.text;
    [self.navigationController pushViewController:SecondView animated:YES];

[self.navigationController popViewControllerAnimated:YES];