在第一次运行时加载不同的视图[重复]

Question

我目前正在编写一个应用程序，该应用程序需要在第一次运行时加载一个不同的视图，用户可以在其中选择其首选设置。这是代码

实现AppDelegate.m

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

// Determining Storyboard identifier for first view
// Determining Storyboard identifier for first view
NSString *storyboardID = [self hasEverBeenLaunched]? @"MainView" : @"LoginView";
// Setting proper view as a rootViewController
self.window.rootViewController = [self.window.rootViewController.storyboardinstantiateViewControllerWithIdentifier: @"view45"] ;

然后继续下面的代码：

- (BOOL)hasEverBeenLaunched
{
// A boolean which determines if app has eer been launched
BOOL hasBeenLaunched;

// Testig if application has launched before and if it has to show the home-login screen        to login
// to social networks (facebook, Twitter)
if ([[NSUserDefaults standardUserDefaults] boolForKey:@"HasAlreadyLaunched"]) {
// Setting variable to YES because app has been launched before
hasBeenLaunched = YES;
 NSLog(@"App has been already launched");
} else {
// Setting variable to NO because app hasn't been launched before
hasBeenLaunched = NO;

[[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"HasAlreadyLaunched"];
[[NSUserDefaults standardUserDefaults] synchronize];
 NSLog(@"This is the first run ever...");
}

return hasBeenLaunched;
}

只是一些简短的说明：视图 45 是初始启动视图，它应该只显示一次，否则主视图控制器在属性下被勾选为初始视图控制器（总是在开始时加载的那个，之后第一次运行）

所以问题是它只加载视图 45，即第一个运行视图，但究竟是什么原因造成的呢？

Answer 1

问题出在下面一行：

self.window.rootViewController = [self.window.rootViewController.storyboardinstantiateViewControllerWithIdentifier: @"view45"] ;

它忽略了storyboardID 的值，只使用字符串@"view45"，所以这就是为什么你每次都会得到相同的值。

如果要修复它，将其更改为以下行：

self.window.rootViewController = [self.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:storyboardID];

您可以看到它现在正在使用 storyboardID 中的值。