ios--appDelegate切换根视图rootViewController(最常用的场合是首次启动跳至导航ViewController)

1、在appDelegate中添加一个切换的方法switchRootViewController:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        
    if ([[NSUserDefaults standardUserDefaults] boolForKey:@"firstLaunch"]) {
        //第一次启动导航页
        NSLog(@"wanggsx:第一次启动");
        ViewController *appStartController = [[ViewController alloc] init];
        self.window.rootViewController = appStartController;
        [self.window addSubview:appStartController.view];
    }
    else
    {
        //打开选择场地界面
        [self switchRootViewController];
    }
    [self.window makeKeyAndVisible];
    return YES;
}

//切换RootViewController
- (void)switchRootViewController
{
    self.window.rootViewController = nil;
    ChooseModeViewController* crBrandsViewController= [[ChooseModeViewController alloc] init];
    UINavigationController *brandsNavigationController = [self customControllerWithRootViewController:crBrandsViewController];
    self.viewController = brandsNavigationController;
    self.window.rootViewController = self.viewController;
}

2、在需要切换根视图的ViewController中调用appDelegate中的方法：

- (IBAction)gotoMainView:(id)sender {
    [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"firstLaunch"];
    [(AppDelegate*)[UIApplication sharedApplication].delegate switchRootViewController];
}