iphone - NSUserDefaults 记住 View

Question

我的应用程序包含几个 View ，我想在应用程序启动且用户尚未完成向导时显示一个小设置。我知道我可以使用 NSUserDefaults 实现此目的，但我不确定如何使其根据 NSUserDefaults 存储的输入字符串显示特定 View 。

我的AppDelegate.m:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    NSString *controllerName = [[NSUserDefaults standardUserDefaults] objectForKey:@"WIZARD_VIEW"];
    if ([controllerName length]) {
        Class controllerClass = NSClassFromString(controllerName);
        UIViewController *controller = [[controllerClass alloc] init];

    // Override point for customization after application launch.
    return YES;
    }

然后在 viewcontroller 文件中，我根据 jfaller 的建议添加了以下代码:

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    NSUserDefaults* standard=[NSUserDefaults standardUserDefaults];
    [standard registerDefaults: @{ @"WIZARD_VIEW" : [[self class]description]} ];    [[NSUserDefaults standardUserDefaults] synchronize];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    NSUserDefaults* standard=[NSUserDefaults standardUserDefaults];
    [standard registerDefaults: @{ @"WIZARD_VIEW" : [[self class]description]} ];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

但是我怎样才能做到这一点，以便它显示在设置中选择的特定 View ？

Answer 1

就我个人而言，我会执行以下操作:

每次用户进入向导中的新 View 时，请在用户默认值中记录 UIViewController:

- (void)viewWillAppear:(BOOL)animated {
  [super viewWillAppear:animated];
  [[NSUserDefaults standardUserDefaults] setObject:[[self class] description] forKey:WIZARD_VIEW];
  [[NSUserDefault standardUserDefaults] synchronize];
}

- (void)viewWillDisappear:(BOOL)animated {
  [super viewWillDisappear:animated];
  [[NSUserDefaults standardUserDefaults] removeObjectForKey:WIZARD_VIEW];
  [[NSUserDefault standardUserDefaults] synchronize];
}

当用户重新启动应用程序时(假设在向导中间)，重新加载 View :

- (BOOL)application:(UIApplication *)application
    willFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  // etc.
  NSString *controllerName = [[NSUserDefaults standardUserDefaults] objectForKey:WIZARD_VIEW];
  if ([controllerName length]) {
    Class controllerClass = NSClassFromString(controllerName); 
    NSViewController *controller = [[controllerClass alloc] init];
    // push the controller, or whatever....
  }
  // etc.
}