Question

我的应用程序包含几个视图，我想在应用程序启动时显示一个小设置，但用户尚未完成向导。我知道我可以使用NSUserDefaults实现这一点，但我不确定如何根据NSUserDefaults存储的输入字符串显示特定视图。

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，我添加了以下代码作为来自jfaller的建议：

- (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];
}

但是我该怎么做才能显示在设置中选择的特定视图？

Answer 1

就个人而言，我会做以下事情：

每次用户转到向导中的新视图时，都会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），重新加载视图：

- (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.
}

Answer 2

在视图加载时将您所查看的视图写入NSUserDefaults。然后检查didFinishLaunchingWithOptions中的值。

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

    if ([[[NSUserDefaults standardUserDefaults] valueForKey:@"current_setup"] isEqualToString:@"1"]) {

         //on view 1!   

    }

}

NSUserDefaults记住了视图

2 个答案: